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Updated: Thursday, March 14, 2019
 
 

scons (1)

Name

scons - a software construction tool

Synopsis

scons [options...] [name=val...] [targets...]

Description

SCONS(1)                          SCons 2.5.1                         SCONS(1)



NAME
       scons - a software construction tool

SYNOPSIS
       scons [options...] [name=val...] [targets...]

DESCRIPTION
       The scons utility builds software (or other files) by determining which
       component pieces must be rebuilt and executing the necessary commands
       to rebuild them.

       By default, scons searches for a file named SConstruct, Sconstruct, or
       sconstruct (in that order) in the current directory and reads its
       configuration from the first file found. An alternate file name may be
       specified via the -f option.

       The SConstruct file can specify subsidiary configuration files using
       the SConscript() function. By convention, these subsidiary files are
       named SConscript, although any name may be used. (Because of this
       naming convention, the term "SConscript files" is sometimes used to
       refer generically to all scons configuration files, regardless of
       actual file name.)

       The configuration files specify the target files to be built, and
       (optionally) the rules to build those targets. Reasonable default rules
       exist for building common software components (executable programs,
       object files, libraries), so that for most software projects, only the
       target and input files need be specified.

       Before reading the SConstruct file, scons looks for a directory named
       site_scons in various system directories (see below) and the directory
       containing the SConstruct file; for each of those dirs which exists,
       site_scons is prepended to sys.path, the file site_scons/site_init.py,
       is evaluated if it exists, and the directory site_scons/site_tools is
       prepended to the default toolpath if it exists. See the --no-site-dir
       and --site-dir options for more details.

       scons reads and executes the SConscript files as Python scripts, so you
       may use normal Python scripting capabilities (such as flow control,
       data manipulation, and imported Python libraries) to handle complicated
       build situations.  scons, however, reads and executes all of the
       SConscript files before it begins building any targets. To make this
       obvious, scons prints the following messages about what it is doing:

           $ scons foo.out
           scons: Reading SConscript files ...
           scons: done reading SConscript files.
           scons: Building targets  ...
           cp foo.in foo.out
           scons: done building targets.
           $

       The status messages (everything except the line that reads "cp foo.in
       foo.out") may be suppressed using the -Q option.

       scons does not automatically propagate the external environment used to
       execute scons to the commands used to build target files. This is so
       that builds will be guaranteed repeatable regardless of the environment
       variables set at the time scons is invoked. This also means that if the
       compiler or other commands that you want to use to build your target
       files are not in standard system locations, scons will not find them
       unless you explicitly set the PATH to include those locations. Whenever
       you create an scons construction environment, you can propagate the
       value of PATH from your external environment as follows:

           import os
           env = Environment(ENV = {'PATH' : os.environ['PATH']})

       Similarly, if the commands use external environment variables like
       $PATH, $HOME, $JAVA_HOME, $LANG, $SHELL, $TERM, etc., these variables
       can also be explicitly propagated:

           import os
           env = Environment(ENV = {'PATH' : os.environ['PATH'],
                                    'HOME' : os.environ['HOME']})

       Or you may explicitly propagate the invoking user's complete external
       environment:

           import os
           env = Environment(ENV = os.environ)

       This comes at the expense of making your build dependent on the user's
       environment being set correctly, but it may be more convenient for many
       configurations.

       scons can scan known input files automatically for dependency
       information (for example, #include statements in C or C++ files) and
       will rebuild dependent files appropriately whenever any "included"
       input file changes.  scons supports the ability to define new scanners
       for unknown input file types.

       scons knows how to fetch files automatically from SCCS or RCS
       subdirectories using SCCS, RCS or BitKeeper.

       scons is normally executed in a top-level directory containing a
       SConstruct file, optionally specifying as command-line arguments the
       target file or files to be built.

       By default, the command

           scons

       will build all target files in or below the current directory. Explicit
       default targets (to be built when no targets are specified on the
       command line) may be defined the SConscript file(s) using the Default()
       function, described below.

       Even when Default() targets are specified in the SConscript file(s),
       all target files in or below the current directory may be built by
       explicitly specifying the current directory (.) as a command-line
       target:

           scons .

       Building all target files, including any files outside of the current
       directory, may be specified by supplying a command-line target of the
       root directory (on POSIX systems):

           scons /

       or the path name(s) of the volume(s) in which all the targets should be
       built (on Windows systems):

           scons C:\ D:\

       To build only specific targets, supply them as command-line arguments:

           scons foo bar

       in which case only the specified targets will be built (along with any
       derived files on which they depend).

       Specifying "cleanup" targets in SConscript files is not usually
       necessary. The -c flag removes all files necessary to build the
       specified target:

           scons -c .

       to remove all target files, or:

           scons -c build export

       to remove target files under build and export. Additional files or
       directories to remove can be specified using the Clean() function.
       Conversely, targets that would normally be removed by the -c invocation
       can be prevented from being removed by using the NoClean() function.

       A subset of a hierarchical tree may be built by remaining at the
       top-level directory (where the SConstruct file lives) and specifying
       the subdirectory as the target to be built:

           scons src/subdir

       or by changing directory and invoking scons with the -u option, which
       traverses up the directory hierarchy until it finds the SConstruct
       file, and then builds targets relatively to the current subdirectory:

           cd src/subdir
           scons -u .

       scons supports building multiple targets in parallel via a -j option
       that takes, as its argument, the number of simultaneous tasks that may
       be spawned:

           scons -j 4

       builds four targets in parallel, for example.

       scons can maintain a cache of target (derived) files that can be shared
       between multiple builds. When caching is enabled in a SConscript file,
       any target files built by scons will be copied to the cache. If an
       up-to-date target file is found in the cache, it will be retrieved from
       the cache instead of being rebuilt locally. Caching behavior may be
       disabled and controlled in other ways by the --cache-force,
       --cache-disable, --cache-readonly, and --cache-show command-line
       options. The --random option is useful to prevent multiple builds from
       trying to update the cache simultaneously.

       Values of variables to be passed to the SConscript file(s) may be
       specified on the command line:

           scons debug=1 .

       These variables are available in SConscript files through the ARGUMENTS
       dictionary, and can be used in the SConscript file(s) to modify the
       build in any way:

           if ARGUMENTS.get('debug', 0):
               env = Environment(CCFLAGS = '-g')
           else:
               env = Environment()

       The command-line variable arguments are also available in the ARGLIST
       list, indexed by their order on the command line. This allows you to
       process them in order rather than by name, if necessary. ARGLIST[0]
       returns a tuple containing (argname, argvalue). A Python exception is
       thrown if you try to access a list member that does not exist.

       scons requires Python version 2.7 or later. There should be no other
       dependencies or requirements to run scons.

       By default, scons knows how to search for available programming tools
       on various systems. On Windows systems, scons searches in order for the
       Microsoft Visual C++ tools, the MinGW tool chain, the Intel compiler
       tools, and the PharLap ETS compiler. On OS/2 systems, scons searches in
       order for the OS/2 compiler, the GCC tool chain, and the Microsoft
       Visual C++ tools, On SGI IRIX, IBM AIX, Hewlett Packard HP-UX, and Sun
       Solaris systems, scons searches for the native compiler tools (MIPSpro,
       Visual Age, aCC, and Forte tools respectively) and the GCC tool chain.
       On all other platforms, including POSIX (Linux and UNIX) platforms,
       scons searches in order for the GCC tool chain, the Microsoft Visual
       C++ tools, and the Intel compiler tools. You may, of course, override
       these default values by appropriate configuration of Environment
       construction variables.

OPTIONS
       In general, scons supports the same command-line options as GNU make,
       and many of those supported by cons.

       -b
           Ignored for compatibility with non-GNU versions of make.

       -c, --clean, --remove
           Clean up by removing all target files for which a construction
           command is specified. Also remove any files or directories
           associated to the construction command using the Clean() function.
           Will not remove any targets specified by the NoClean() function.

       --cache-debug=file
           Print debug information about the CacheDir() derived-file caching
           to the specified file. If file is - (a hyphen), the debug
           information are printed to the standard output. The printed
           messages describe what signature file names are being looked for
           in, retrieved from, or written to the CacheDir() directory tree.

       --cache-disable, --no-cache
           Disable the derived-file caching specified by CacheDir().  scons
           will neither retrieve files from the cache nor copy files to the
           cache.

       --cache-force, --cache-populate
           When using CacheDir(), populate a cache by copying any
           already-existing, up-to-date derived files to the cache, in
           addition to files built by this invocation. This is useful to
           populate a new cache with all the current derived files, or to add
           to the cache any derived files recently built with caching disabled
           via the --cache-disable option.

       --cache-readonly
           Use the cache (if enabled) for reading, but do not not update the
           cache with changed files.

       --cache-show
           When using CacheDir() and retrieving a derived file from the cache,
           show the command that would have been executed to build the file,
           instead of the usual report, "Retrieved `file' from cache." This
           will produce consistent output for build logs, regardless of
           whether a target file was rebuilt or retrieved from the cache.

       --config=mode
           This specifies how the Configure call should use or generate the
           results of configuration tests. The option should be specified from
           among the following choices:

       --config=auto
           scons will use its normal dependency mechanisms to decide if a test
           must be rebuilt or not. This saves time by not running the same
           configuration tests every time you invoke scons, but will overlook
           changes in system header files or external commands (such as
           compilers) if you don't specify those dependecies explicitly. This
           is the default behavior.

       --config=force
           If this option is specified, all configuration tests will be re-run
           regardless of whether the cached results are out of date. This can
           be used to explicitly force the configuration tests to be updated
           in response to an otherwise unconfigured change in a system header
           file or compiler.

       --config=cache
           If this option is specified, no configuration tests will be rerun
           and all results will be taken from cache. Note that scons will
           still consider it an error if --config=cache is specified and a
           necessary test does not yet have any results in the cache.

       -C directory, --directory=directory
           Change to the specified directory before searching for the
           SConstruct, Sconstruct, or sconstruct file, or doing anything else.
           Multiple -C options are interpreted relative to the previous one,
           and the right-most -C option wins. (This option is nearly
           equivalent to -f directory/SConstruct, except that it will search
           for SConstruct, Sconstruct, or sconstruct in the specified
           directory.)

       -D
           Works exactly the same way as the -u option except for the way
           default targets are handled. When this option is used and no
           targets are specified on the command line, all default targets are
           built, whether or not they are below the current directory.

       --debug=type
           Debug the build process.  type[,type...]  specifies what type of
           debugging. Multiple types may be specified, separated by commas.
           The following types are valid:

       --debug=count
           Print how many objects are created of the various classes used
           internally by SCons before and after reading the SConscript files
           and before and after building targets. This is not supported when
           SCons is executed with the Python -O (optimized) option or when the
           SCons modules have been compiled with optimization (that is, when
           executing from *.pyo files).

       --debug=duplicate
           Print a line for each unlink/relink (or copy) of a variant file
           from its source file. Includes debugging info for unlinking stale
           variant files, as well as unlinking old targets before building
           them.

       --debug=dtree
           A synonym for the newer --tree=derived option. This will be
           deprecated in some future release and ultimately removed.

       --debug=explain
           Print an explanation of precisely why scons is deciding to
           (re-)build any targets. (Note: this does not print anything for
           targets that are not rebuilt.)

       --debug=findlibs
           Instruct the scanner that searches for libraries to print a message
           about each potential library name it is searching for, and about
           the actual libraries it finds.

       --debug=includes
           Print the include tree after each top-level target is built. This
           is generally used to find out what files are included by the
           sources of a given derived file:

               $ scons --debug=includes foo.o

       --debug=memoizer
           Prints a summary of hits and misses using the Memoizer, an internal
           subsystem that counts how often SCons uses cached values in memory
           instead of recomputing them each time they're needed.

       --debug=memory
           Prints how much memory SCons uses before and after reading the
           SConscript files and before and after building targets.

       --debug=nomemoizer
           A deprecated option preserved for backwards compatibility.

       --debug=objects
           Prints a list of the various objects of the various classes used
           internally by SCons.

       --debug=pdb
           Re-run SCons under the control of the pdb Python debugger.

       --debug=prepare
           Print a line each time any target (internal or external) is
           prepared for building.  scons prints this for each target it
           considers, even if that target is up to date (see also
           --debug=explain). This can help debug problems with targets that
           aren't being built; it shows whether scons is at least considering
           them or not.

       --debug=presub
           Print the raw command line used to build each target before the
           construction environment variables are substituted. Also shows
           which targets are being built by this command. Output looks
           something like this:

               $ scons --debug=presub
               Building myprog.o with action(s):
                 $SHCC $SHCFLAGS $SHCCFLAGS $CPPFLAGS $_CPPINCFLAGS -c -o $TARGET $SOURCES
               ...

       --debug=stacktrace
           Prints an internal Python stack trace when encountering an
           otherwise unexplained error.

       --debug=stree
           A synonym for the newer --tree=all,status option. This will be
           deprecated in some future release and ultimately removed.

       --debug=time
           Prints various time profiling information: the time spent executing
           each individual build command; the total build time (time SCons ran
           from beginning to end); the total time spent reading and executing
           SConscript files; the total time spent SCons itself spend running
           (that is, not counting reading and executing SConscript files); and
           both the total time spent executing all build commands and the
           elapsed wall-clock time spent executing those build commands. (When
           scons is executed without the -j option, the elapsed wall-clock
           time will typically be slightly longer than the total time spent
           executing all the build commands, due to the SCons processing that
           takes place in between executing each command. When scons is
           executed with the -j option, and your build configuration allows
           good parallelization, the elapsed wall-clock time should be
           significantly smaller than the total time spent executing all the
           build commands, since multiple build commands and intervening SCons
           processing should take place in parallel.)

       --debug=tree
           A synonym for the newer --tree=all option. This will be deprecated
           in some future release and ultimately removed.

       --diskcheck=types
           Enable specific checks for whether or not there is a file on disk
           where the SCons configuration expects a directory (or vice versa),
           and whether or not RCS or SCCS sources exist when searching for
           source and include files. The types argument can be set to: all, to
           enable all checks explicitly (the default behavior); none, to
           disable all such checks; match, to check that files and directories
           on disk match SCons' expected configuration; rcs, to check for the
           existence of an RCS source for any missing source or include files;
           sccs, to check for the existence of an SCCS source for any missing
           source or include files. Multiple checks can be specified separated
           by commas; for example, --diskcheck=sccs,rcs would still check for
           SCCS and RCS sources, but disable the check for on-disk matches of
           files and directories. Disabling some or all of these checks can
           provide a performance boost for large configurations, or when the
           configuration will check for files and/or directories across
           networked or shared file systems, at the slight increased risk of
           an incorrect build or of not handling errors gracefully (if include
           files really should be found in SCCS or RCS, for example, or if a
           file really does exist where the SCons configuration expects a
           directory).

       --duplicate=ORDER
           There are three ways to duplicate files in a build tree: hard
           links, soft (symbolic) links and copies. The default behaviour of
           SCons is to prefer hard links to soft links to copies. You can
           specify different behaviours with this option.  ORDER must be one
           of hard-soft-copy (the default), soft-hard-copy, hard-copy,
           soft-copy or copy. SCons will attempt to duplicate files using the
           mechanisms in the specified order.

       -f file, --file=file, --makefile=file, --sconstruct=file
           Use file as the initial SConscript file. Multiple -f options may be
           specified, in which case scons will read all of the specified
           files.

       -h, --help
           Print a local help message for this build, if one is defined in the
           SConscript file(s), plus a line that describes the -H option for
           command-line option help. If no local help message is defined,
           prints the standard help message about command-line options. Exits
           after displaying the appropriate message.

       -H, --help-options
           Print the standard help message about command-line options and
           exit.

       -i, --ignore-errors
           Ignore all errors from commands executed to rebuild files.

       -I directory, --include-dir=directory
           Specifies a directory to search for imported Python modules. If
           several -I options are used, the directories are searched in the
           order specified.

       --implicit-cache
           Cache implicit dependencies. This causes scons to use the implicit
           (scanned) dependencies from the last time it was run instead of
           scanning the files for implicit dependencies. This can
           significantly speed up SCons, but with the following limitations:

       scons will not detect changes to implicit dependency search paths (e.g.
       CPPPATH, LIBPATH) that would ordinarily cause different versions of
       same-named files to be used.

       scons will miss changes in the implicit dependencies in cases where a
       new implicit dependency is added earlier in the implicit dependency
       search path (e.g.  CPPPATH, LIBPATH) than a current implicit dependency
       with the same name.

       --implicit-deps-changed
           Forces SCons to ignore the cached implicit dependencies. This
           causes the implicit dependencies to be rescanned and recached. This
           implies --implicit-cache.

       --implicit-deps-unchanged
           Force SCons to ignore changes in the implicit dependencies. This
           causes cached implicit dependencies to always be used. This implies
           --implicit-cache.

       --interactive
           Starts SCons in interactive mode. The SConscript files are read
           once and a scons>>> prompt is printed. Targets may now be rebuilt
           by typing commands at interactive prompt without having to re-read
           the SConscript files and re-initialize the dependency graph from
           scratch.

           SCons interactive mode supports the following commands:

           build[OPTIONS] [TARGETS] ...
               Builds the specified TARGETS (and their dependencies) with the
               specified SCons command-line OPTIONS.  b and scons are
               synonyms.

               The following SCons command-line options affect the build
               command:

                   --cache-debug=FILE
                   --cache-disable, --no-cache
                   --cache-force, --cache-populate
                   --cache-readonly
                   --cache-show
                   --debug=TYPE
                   -i, --ignore-errors
                   -j N, --jobs=N
                   -k, --keep-going
                   -n, --no-exec, --just-print, --dry-run, --recon
                   -Q
                   -s, --silent, --quiet
                   --taskmastertrace=FILE
                   --tree=OPTIONS

           Any other SCons command-line options that are specified do not
           cause errors but have no effect on the build command (mainly
           because they affect how the SConscript files are read, which only
           happens once at the beginning of interactive mode).

           clean[OPTIONS] [TARGETS] ...
               Cleans the specified TARGETS (and their dependencies) with the
               specified options.  c is a synonym. This command is itself a
               synonym for build --clean

           exit
               Exits SCons interactive mode. You can also exit by terminating
               input (CTRL+D on UNIX or Linux systems, CTRL+Z on Windows
               systems).

           help[COMMAND]
               Provides a help message about the commands available in SCons
               interactive mode. If COMMAND is specified, h and ?  are
               synonyms.

           shell[COMMANDLINE]
               Executes the specified COMMANDLINE in a subshell. If no
               COMMANDLINE is specified, executes the interactive command
               interpreter specified in the SHELL environment variable (on
               UNIX and Linux systems) or the COMSPEC environment variable (on
               Windows systems).  sh and !  are synonyms.

           version
               Prints SCons version information.

       An empty line repeats the last typed command. Command-line editing can
       be used if the readline module is available.

           $ scons --interactive
           scons: Reading SConscript files ...
           scons: done reading SConscript files.
           scons>>> build -n prog
           scons>>> exit

       -j N, --jobs=N
           Specifies the number of jobs (commands) to run simultaneously. If
           there is more than one -j option, the last one is effective.

       -k, --keep-going
           Continue as much as possible after an error. The target that failed
           and those that depend on it will not be remade, but other targets
           specified on the command line will still be processed.

       -m
           Ignored for compatibility with non-GNU versions of make.

       --max-drift=SECONDS
           Set the maximum expected drift in the modification time of files to
           SECONDS. This value determines how long a file must be unmodified
           before its cached content signature will be used instead of
           calculating a new content signature (MD5 checksum) of the file's
           contents. The default value is 2 days, which means a file must have
           a modification time of at least two days ago in order to have its
           cached content signature used. A negative value means to never
           cache the content signature and to ignore the cached value if there
           already is one. A value of 0 means to always use the cached
           signature, no matter how old the file is.

       --md5-chunksize=KILOBYTES
           Set the block size used to compute MD5 signatures to KILOBYTES.
           This value determines the size of the chunks which are read in at
           once when computing MD5 signatures. Files below that size are fully
           stored in memory before performing the signature computation while
           bigger files are read in block-by-block. A huge block-size leads to
           high memory consumption while a very small block-size slows down
           the build considerably.

           The default value is to use a chunk size of 64 kilobytes, which
           should be appropriate for most uses.

       -n, --just-print, --dry-run, --recon
           No execute. Print the commands that would be executed to build any
           out-of-date target files, but do not execute the commands.

       --no-site-dir
           Prevents the automatic addition of the standard site_scons dirs to
           sys.path. Also prevents loading the site_scons/site_init.py modules
           if they exist, and prevents adding their site_scons/site_tools dirs
           to the toolpath.

       --profile=file
           Run SCons under the Python profiler and save the results in the
           specified file. The results may be analyzed using the Python pstats
           module.

       -q, --question
           Do not run any commands, or print anything. Just return an exit
           status that is zero if the specified targets are already up to
           date, non-zero otherwise.

       -Q
           Quiets SCons status messages about reading SConscript files,
           building targets and entering directories. Commands that are
           executed to rebuild target files are still printed.

       --random
           Build dependencies in a random order. This is useful when building
           multiple trees simultaneously with caching enabled, to prevent
           multiple builds from simultaneously trying to build or retrieve the
           same target files.

       -s, --silent, --quiet
           Silent. Do not print commands that are executed to rebuild target
           files. Also suppresses SCons status messages.

       -S, --no-keep-going, --stop
           Ignored for compatibility with GNU make.

       --site-dir=dir
           Uses the named dir as the site dir rather than the default
           site_scons dirs. This dir will get prepended to sys.path, the
           module dir/site_init.py will get loaded if it exists, and
           dir/site_tools will get added to the default toolpath.

           The default set of site_scons dirs used when --site-dir is not
           specified depends on the system platform, as follows. Note that the
           directories are examined in the order given, from most generic to
           most specific, so the last-executed site_init.py file is the most
           specific one (which gives it the chance to override everything
           else), and the dirs are prepended to the paths, again so the last
           dir examined comes first in the resulting path.

       Windows:

               %ALLUSERSPROFILE/Application Data/scons/site_scons
               %USERPROFILE%/Local Settings/Application Data/scons/site_scons
               %APPDATA%/scons/site_scons
               %HOME%/.scons/site_scons
               ./site_scons

       Mac OS X:

               /Library/Application Support/SCons/site_scons
               /opt/local/share/scons/site_scons (for MacPorts)
               /sw/share/scons/site_scons (for Fink)
               $HOME/Library/Application Support/SCons/site_scons
               $HOME/.scons/site_scons
               ./site_scons

       Solaris:

               /opt/sfw/scons/site_scons
               /usr/share/scons/site_scons
               $HOME/.scons/site_scons
               ./site_scons

       Linux, HPUX, and other Posix-like systems:

               /usr/share/scons/site_scons
               $HOME/.scons/site_scons
               ./site_scons

       --stack-size=KILOBYTES
           Set the size stack used to run threads to KILOBYTES. This value
           determines the stack size of the threads used to run jobs. These
           are the threads that execute the actions of the builders for the
           nodes that are out-of-date. Note that this option has no effect
           unless the num_jobs option, which corresponds to -j and --jobs, is
           larger than one. Using a stack size that is too small may cause
           stack overflow errors. This usually shows up as segmentation faults
           that cause scons to abort before building anything. Using a stack
           size that is too large will cause scons to use more memory than
           required and may slow down the entire build process.

           The default value is to use a stack size of 256 kilobytes, which
           should be appropriate for most uses. You should not need to
           increase this value unless you encounter stack overflow errors.

       -t, --touch
           Ignored for compatibility with GNU make. (Touching a file to make
           it appear up-to-date is unnecessary when using scons.)

       --taskmastertrace=file
           Prints trace information to the specified file about how the
           internal Taskmaster object evaluates and controls the order in
           which Nodes are built. A file name of - may be used to specify the
           standard output.

       -tree=options
           Prints a tree of the dependencies after each top-level target is
           built. This prints out some or all of the tree, in various formats,
           depending on the options specified:

       --tree=all
           Print the entire dependency tree after each top-level target is
           built. This prints out the complete dependency tree, including
           implicit dependencies and ignored dependencies.

       --tree=derived
           Restricts the tree output to only derived (target) files, not
           source files.

       --tree=status
           Prints status information for each displayed node.

       --tree=prune
           Prunes the tree to avoid repeating dependency information for nodes
           that have already been displayed. Any node that has already been
           displayed will have its name printed in [square brackets], as an
           indication that the dependencies for that node can be found by
           searching for the relevant output higher up in the tree.

       Multiple options may be specified, separated by commas:

           # Prints only derived files, with status information:
           scons --tree=derived,status

           # Prints all dependencies of target, with status information
           # and pruning dependencies of already-visited Nodes:
           scons --tree=all,prune,status target

       -u, --up, --search-up
           Walks up the directory structure until an SConstruct , Sconstruct
           or sconstruct file is found, and uses that as the top of the
           directory tree. If no targets are specified on the command line,
           only targets at or below the current directory will be built.

       -U
           Works exactly the same way as the -u option except for the way
           default targets are handled. When this option is used and no
           targets are specified on the command line, all default targets that
           are defined in the SConscript(s) in the current directory are
           built, regardless of what directory the resultant targets end up
           in.

       -v, --version
           Print the scons version, copyright information, list of authors,
           and any other relevant information. Then exit.

       -w, --print-directory
           Print a message containing the working directory before and after
           other processing.

       --no-print-directory
           Turn off -w, even if it was turned on implicitly.

       --warn=type, --warn=no-type
           Enable or disable warnings.  type specifies the type of warnings to
           be enabled or disabled:

       --warn=all, --warn=no-all
           Enables or disables all warnings.

       --warn=cache-version, --warn=no-cache-version
           Enables or disables warnings about the cache directory not using
           the latest configuration information CacheDir(). These warnings are
           enabled by default.

       --warn=cache-write-error, --warn=no-cache-write-error
           Enables or disables warnings about errors trying to write a copy of
           a built file to a specified CacheDir(). These warnings are disabled
           by default.

       --warn=corrupt-sconsign, --warn=no-corrupt-sconsign
           Enables or disables warnings about unfamiliar signature data in
           .sconsign files. These warnings are enabled by default.

       --warn=dependency, --warn=no-dependency
           Enables or disables warnings about dependencies. These warnings are
           disabled by default.

       --warn=deprecated, --warn=no-deprecated
           Enables or disables all warnings about use of currently deprecated
           features. These warnings are enabled by default. Note that the
           --warn=no-deprecated option does not disable warnings about
           absolutely all deprecated features. Warnings for some deprecated
           features that have already been through several releases with
           deprecation warnings may be mandatory for a release or two before
           they are officially no longer supported by SCons. Warnings for some
           specific deprecated features may be enabled or disabled
           individually; see below.

           --warn=deprecated-copy, --warn=no-deprecated-copy
               Enables or disables warnings about use of the deprecated
               env.Copy() method.

           --warn=deprecated-source-signatures,
           --warn=no-deprecated-source-signatures
               Enables or disables warnings about use of the deprecated
               SourceSignatures() function or env.SourceSignatures() method.

           --warn=deprecated-target-signatures,
           --warn=no-deprecated-target-signatures
               Enables or disables warnings about use of the deprecated
               TargetSignatures() function or env.TargetSignatures() method.

       --warn=duplicate-environment, --warn=no-duplicate-environment
           Enables or disables warnings about attempts to specify a build of a
           target with two different construction environments that use the
           same action. These warnings are enabled by default.

       --warn=fortran-cxx-mix, --warn=no-fortran-cxx-mix
           Enables or disables the specific warning about linking Fortran and
           C++ object files in a single executable, which can yield
           unpredictable behavior with some compilers.

       --warn=future-deprecated, --warn=no-future-deprecated
           Enables or disables warnings about features that will be deprecated
           in the future. These warnings are disabled by default. Enabling
           this warning is especially recommended for projects that
           redistribute SCons configurations for other users to build, so that
           the project can be warned as soon as possible about
           to-be-deprecated features that may require changes to the
           configuration.

       --warn=link, --warn=no-link
           Enables or disables warnings about link steps.

       --warn=misleading-keywords, --warn=no-misleading-keywords
           Enables or disables warnings about use of the misspelled keywords
           targets and sources when calling Builders. (Note the last s
           characters, the correct spellings are target and source.)  These
           warnings are enabled by default.

       --warn=missing-sconscript, --warn=no-missing-sconscript
           Enables or disables warnings about missing SConscript files. These
           warnings are enabled by default.

       --warn=no-md5-module, --warn=no-no-md5-module
           Enables or disables warnings about the version of Python not having
           an MD5 checksum module available. These warnings are enabled by
           default.

       --warn=no-metaclass-support, --warn=no-no-metaclass-support
           Enables or disables warnings about the version of Python not
           supporting metaclasses when the --debug=memoizer option is used.
           These warnings are enabled by default.

       --warn=no-object-count, --warn=no-no-object-count
           Enables or disables warnings about the --debug=object feature not
           working when scons is run with the python -O option or from
           optimized Python (.pyo) modules.

       --warn=no-parallel-support, --warn=no-no-parallel-support
           Enables or disables warnings about the version of Python not being
           able to support parallel builds when the -j option is used. These
           warnings are enabled by default.

       --warn=python-version, --warn=no-python-version
           Enables or disables the warning about running SCons with a
           deprecated version of Python. These warnings are enabled by
           default.

       --warn=reserved-variable, --warn=no-reserved-variable
           Enables or disables warnings about attempts to set the reserved
           construction variable names CHANGED_SOURCES, CHANGED_TARGETS,
           TARGET, TARGETS, SOURCE, SOURCES, UNCHANGED_SOURCES or
           UNCHANGED_TARGETS. These warnings are disabled by default.

       --warn=stack-size, --warn=no-stack-size
           Enables or disables warnings about requests to set the stack size
           that could not be honored. These warnings are enabled by default.

       --warn=target_not_build, --warn=no-target_not_built
           Enables or disables warnings about a build rule not building the
           expected targets. These warnings are not currently enabled by
           default.

       -Y repository, --repository=repository, --srcdir=repository
           Search the specified repository for any input and target files not
           found in the local directory hierarchy. Multiple -Y options may be
           specified, in which case the repositories are searched in the order
           specified.

CONFIGURATION FILE REFERENCE
   Construction Environments
       A construction environment is the basic means by which the SConscript
       files communicate build information to scons. A new construction
       environment is created using the Environment function:

           env = Environment()

       Variables, called construction variables, may be set in a construction
       environment either by specifying them as keywords when the object is
       created or by assigning them a value after the object is created:

           env = Environment(FOO = 'foo')
           env['BAR'] = 'bar'

       As a convenience, construction variables may also be set or modified by
       the parse_flags keyword argument, which applies the ParseFlags method
       (described below) to the argument value after all other processing is
       completed. This is useful either if the exact content of the flags is
       unknown (for example, read from a control file) or if the flags are
       distributed to a number of construction variables.

           env = Environment(parse_flags = '-Iinclude -DEBUG -lm')

       This example adds 'include' to CPPPATH, 'EBUG' to CPPDEFINES, and 'm'
       to LIBS.

       By default, a new construction environment is initialized with a set of
       builder methods and construction variables that are appropriate for the
       current platform. An optional platform keyword argument may be used to
       specify that an environment should be initialized for a different
       platform:

           env = Environment(platform = 'cygwin')
           env = Environment(platform = 'os2')
           env = Environment(platform = 'posix')
           env = Environment(platform = 'win32')

       Specifying a platform initializes the appropriate construction
       variables in the environment to use and generate file names with
       prefixes and suffixes appropriate for the platform.

       Note that the win32 platform adds the SystemDrive and SystemRoot
       variables from the user's external environment to the construction
       environment's ENV dictionary. This is so that any executed commands
       that use sockets to connect with other systems (such as fetching source
       files from external CVS repository specifications like
       :pserver:anonymous@cvs.sourceforge.net:/cvsroot/scons) will work on
       Windows systems.

       The platform argument may be function or callable object, in which case
       the Environment() method will call the specified argument to update the
       new construction environment:

           def my_platform(env):
               env['VAR'] = 'xyzzy'

           env = Environment(platform = my_platform)

       Additionally, a specific set of tools with which to initialize the
       environment may be specified as an optional keyword argument:

           env = Environment(tools = ['msvc', 'lex'])

       Non-built-in tools may be specified using the toolpath argument:

           env = Environment(tools = ['default', 'foo'], toolpath = ['tools'])

       This looks for a tool specification in tools/foo.py (as well as using
       the ordinary default tools for the platform). foo.py should have two
       functions: generate(env, **kw) and exists(env). The generate() function
       modifies the passed-in environment to set up variables so that the tool
       can be executed; it may use any keyword arguments that the user
       supplies (see below) to vary its initialization. The exists() function
       should return a true value if the tool is available. Tools in the
       toolpath are used before any of the built-in ones. For example, adding
       gcc.py to the toolpath would override the built-in gcc tool. Also note
       that the toolpath is stored in the environment for use by later calls
       to Clone() and Tool() methods:

           base = Environment(toolpath=['custom_path'])
           derived = base.Clone(tools=['custom_tool'])
           derived.CustomBuilder()

       The elements of the tools list may also be functions or callable
       objects, in which case the Environment() method will call the specified
       elements to update the new construction environment:

           def my_tool(env):
               env['XYZZY'] = 'xyzzy'

           env = Environment(tools = [my_tool])

       The individual elements of the tools list may also themselves be
       two-element lists of the form (toolname, kw_dict). SCons searches for
       the toolname specification file as described above, and passes kw_dict,
       which must be a dictionary, as keyword arguments to the tool's generate
       function. The generate function can use the arguments to modify the
       tool's behavior by setting up the environment in different ways or
       otherwise changing its initialization.

           # in tools/my_tool.py:
           def generate(env, **kw):
             # Sets MY_TOOL to the value of keyword argument 'arg1' or 1.
             env['MY_TOOL'] = kw.get('arg1', '1')
           def exists(env):
             return 1

           # in SConstruct:
           env = Environment(tools = ['default', ('my_tool', {'arg1': 'abc'})],
                             toolpath=['tools'])

       The tool definition (i.e. my_tool()) can use the PLATFORM variable from
       the environment it receives to customize the tool for different
       platforms.

       If no tool list is specified, then SCons will auto-detect the installed
       tools using the PATH variable in the ENV construction variable and the
       platform name when the Environment is constructed. Changing the PATH
       variable after the Environment is constructed will not cause the tools
       to be redetected.

       SCons supports the following tool specifications out of the box:

       386asm
           Sets construction variables for the 386ASM assembler for the Phar
           Lap ETS embedded operating system.

           Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

           Uses: $CC, $CPPFLAGS, $_CPPDEFFLAGS, $_CPPINCFLAGS.

       aixc++
           Sets construction variables for the IMB xlc / Visual Age C++
           compiler.

           Sets: $CXX, $CXXVERSION, $SHCXX, $SHOBJSUFFIX.

       aixcc
           Sets construction variables for the IBM xlc / Visual Age C
           compiler.

           Sets: $CC, $CCVERSION, $SHCC.

       aixf77
           Sets construction variables for the IBM Visual Age f77 Fortran
           compiler.

           Sets: $F77, $SHF77.

       aixlink
           Sets construction variables for the IBM Visual Age linker.

           Sets: $LINKFLAGS, $SHLIBSUFFIX, $SHLINKFLAGS.

       applelink
           Sets construction variables for the Apple linker (similar to the
           GNU linker).

           Sets: $FRAMEWORKPATHPREFIX, $LDMODULECOM, $LDMODULEFLAGS,
           $LDMODULEPREFIX, $LDMODULESUFFIX, $LINKCOM, $SHLINKCOM,
           $SHLINKFLAGS, $_FRAMEWORKPATH, $_FRAMEWORKS.

           Uses: $FRAMEWORKSFLAGS.

       ar
           Sets construction variables for the ar library archiver.

           Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX, $RANLIB,
           $RANLIBCOM, $RANLIBFLAGS.

       as
           Sets construction variables for the as assembler.

           Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

           Uses: $CC, $CPPFLAGS, $_CPPDEFFLAGS, $_CPPINCFLAGS.

       bcc32
           Sets construction variables for the bcc32 compiler.

           Sets: $CC, $CCCOM, $CCFLAGS, $CFILESUFFIX, $CFLAGS, $CPPDEFPREFIX,
           $CPPDEFSUFFIX, $INCPREFIX, $INCSUFFIX, $SHCC, $SHCCCOM, $SHCCFLAGS,
           $SHCFLAGS, $SHOBJSUFFIX.

           Uses: $_CPPDEFFLAGS, $_CPPINCFLAGS.

       BitKeeper
           Sets construction variables for the BitKeeper source code control
           system.

           Sets: $BITKEEPER, $BITKEEPERCOM, $BITKEEPERGET, $BITKEEPERGETFLAGS.

           Uses: $BITKEEPERCOMSTR.

       cc
           Sets construction variables for generic POSIX C copmilers.

           Sets: $CC, $CCCOM, $CCFLAGS, $CFILESUFFIX, $CFLAGS, $CPPDEFPREFIX,
           $CPPDEFSUFFIX, $FRAMEWORKPATH, $FRAMEWORKS, $INCPREFIX, $INCSUFFIX,
           $SHCC, $SHCCCOM, $SHCCFLAGS, $SHCFLAGS, $SHOBJSUFFIX.

           Uses: $PLATFORM.

       cvf
           Sets construction variables for the Compaq Visual Fortran compiler.

           Sets: $FORTRAN, $FORTRANCOM, $FORTRANMODDIR, $FORTRANMODDIRPREFIX,
           $FORTRANMODDIRSUFFIX, $FORTRANPPCOM, $OBJSUFFIX, $SHFORTRANCOM,
           $SHFORTRANPPCOM.

           Uses: $CPPFLAGS, $FORTRANFLAGS, $SHFORTRANFLAGS, $_CPPDEFFLAGS,
           $_FORTRANINCFLAGS, $_FORTRANMODFLAG.

       CVS
           Sets construction variables for the CVS source code management
           system.

           Sets: $CVS, $CVSCOFLAGS, $CVSCOM, $CVSFLAGS.

           Uses: $CVSCOMSTR.

       cXX
           Sets construction variables for generic POSIX C++ compilers.

           Sets: $CPPDEFPREFIX, $CPPDEFSUFFIX, $CXX, $CXXCOM, $CXXFILESUFFIX,
           $CXXFLAGS, $INCPREFIX, $INCSUFFIX, $OBJSUFFIX, $SHCXX, $SHCXXCOM,
           $SHCXXFLAGS, $SHOBJSUFFIX.

           Uses: $CXXCOMSTR.

       cyglink
           Set construction variables for cygwin linker/loader.

           Sets: $IMPLIBPREFIX, $IMPLIBSUFFIX, $LDMODULEVERSIONFLAGS,
           $LINKFLAGS, $RPATHPREFIX, $RPATHSUFFIX, $SHLIBPREFIX, $SHLIBSUFFIX,
           $SHLIBVERSIONFLAGS, $SHLINKCOM, $SHLINKFLAGS,
           $_LDMODULEVERSIONFLAGS, $_SHLIBVERSIONFLAGS.

       default
           Sets variables by calling a default list of Tool modules for the
           platform on which SCons is running.

       dmd
           Sets construction variables for D language compiler DMD.

           Sets: $DC, $DCOM, $DDEBUG, $DDEBUGPREFIX, $DDEBUGSUFFIX,
           $DFILESUFFIX, $DFLAGPREFIX, $DFLAGS, $DFLAGSUFFIX, $DINCPREFIX,
           $DINCSUFFIX, $DLIB, $DLIBCOM, $DLIBDIRPREFIX, $DLIBDIRSUFFIX,
           $DLIBFLAGPREFIX, $DLIBFLAGSUFFIX, $DLIBLINKPREFIX, $DLIBLINKSUFFIX,
           $DLINK, $DLINKCOM, $DLINKFLAGS, $DPATH, $DVERPREFIX, $DVERSIONS,
           $DVERSUFFIX, $RPATHPREFIX, $RPATHSUFFIX, $SHDC, $SHDCOM, $SHDLINK,
           $SHDLINKCOM, $SHDLINKFLAGS, $_DDEBUGFLAGS, $_DFLAGS, $_DINCFLAGS,
           $_DLIBDIRFLAGS, $_DLIBFLAGS, $_DLIBFLAGS, $_DVERFLAGS, $_RPATH.

       docbook
           This tool tries to make working with Docbook in SCons a little
           easier. It provides several toolchains for creating different
           output formats, like HTML or PDF. Contained in the package is a
           distribution of the Docbook XSL stylesheets as of version 1.76.1.
           As long as you don't specify your own stylesheets for
           customization, these official versions are picked as
           default...which should reduce the inevitable setup hassles for you.

           Implicit dependencies to images and XIncludes are detected
           automatically if you meet the HTML requirements. The additional
           stylesheet utils/xmldepend.xsl by Paul DuBois is used for this
           purpose.

           Note, that there is no support for XML catalog resolving offered!
           This tool calls the XSLT processors and PDF renderers with the
           stylesheets you specified, that's it. The rest lies in your hands
           and you still have to know what you're doing when resolving names
           via a catalog.

           For activating the tool "docbook", you have to add its name to the
           Environment constructor, like this

               env = Environment(tools=['docbook'])

           On its startup, the Docbook tool tries to find a required xsltproc
           processor, and a PDF renderer, e.g.  fop. So make sure that these
           are added to your system's environment PATH and can be called
           directly, without specifying their full path.

           For the most basic processing of Docbook to HTML, you need to have
           installed

           o   the Python lxml binding to libxml2, or

           o   the direct Python bindings for libxml2/libxslt, or

           o   a standalone XSLT processor, currently detected are xsltproc,
               saxon, saxon-xslt and xalan.

           Rendering to PDF requires you to have one of the applications fop
           or xep installed.

           Creating a HTML or PDF document is very simple and straightforward.
           Say

               env = Environment(tools=['docbook'])
               env.DocbookHtml('manual.html', 'manual.xml')
               env.DocbookPdf('manual.pdf', 'manual.xml')

           to get both outputs from your XML source manual.xml. As a shortcut,
           you can give the stem of the filenames alone, like this:

               env = Environment(tools=['docbook'])
               env.DocbookHtml('manual')
               env.DocbookPdf('manual')

           and get the same result. Target and source lists are also
           supported:

               env = Environment(tools=['docbook'])
               env.DocbookHtml(['manual.html','reference.html'], ['manual.xml','reference.xml'])

           or even

               env = Environment(tools=['docbook'])
               env.DocbookHtml(['manual','reference'])


               Important
               Whenever you leave out the list of sources, you may not specify
               a file extension! The Tool uses the given names as file stems,
               and adds the suffixes for target and source files accordingly.
           The rules given above are valid for the Builders DocbookHtml,
           DocbookPdf, DocbookEpub, DocbookSlidesPdf and DocbookXInclude. For
           the DocbookMan transformation you can specify a target name, but
           the actual output names are automatically set from the refname
           entries in your XML source.

           The Builders DocbookHtmlChunked, DocbookHtmlhelp and
           DocbookSlidesHtml are special, in that:

            1. they create a large set of files, where the exact names and
               their number depend on the content of the source file, and

            2. the main target is always named index.html, i.e. the output
               name for the XSL transformation is not picked up by the
               stylesheets.

           As a result, there is simply no use in specifying a target HTML
           name. So the basic syntax for these builders is always:

               env = Environment(tools=['docbook'])
               env.DocbookHtmlhelp('manual')

           If you want to use a specific XSL file, you can set the additional
           xsl parameter to your Builder call as follows:

               env.DocbookHtml('other.html', 'manual.xml', xsl='html.xsl')

           Since this may get tedious if you always use the same local naming
           for your customized XSL files, e.g.  html.xsl for HTML and pdf.xsl
           for PDF output, a set of variables for setting the default XSL name
           is provided. These are:

               DOCBOOK_DEFAULT_XSL_HTML
               DOCBOOK_DEFAULT_XSL_HTMLCHUNKED
               DOCBOOK_DEFAULT_XSL_HTMLHELP
               DOCBOOK_DEFAULT_XSL_PDF
               DOCBOOK_DEFAULT_XSL_EPUB
               DOCBOOK_DEFAULT_XSL_MAN
               DOCBOOK_DEFAULT_XSL_SLIDESPDF
               DOCBOOK_DEFAULT_XSL_SLIDESHTML

           and you can set them when constructing your environment:

               env = Environment(tools=['docbook'],
                                 DOCBOOK_DEFAULT_XSL_HTML='html.xsl',
                                 DOCBOOK_DEFAULT_XSL_PDF='pdf.xsl')
               env.DocbookHtml('manual') # now uses html.xsl

           Sets: $DOCBOOK_DEFAULT_XSL_EPUB, $DOCBOOK_DEFAULT_XSL_HTML,
           $DOCBOOK_DEFAULT_XSL_HTMLCHUNKED, $DOCBOOK_DEFAULT_XSL_HTMLHELP,
           $DOCBOOK_DEFAULT_XSL_MAN, $DOCBOOK_DEFAULT_XSL_PDF,
           $DOCBOOK_DEFAULT_XSL_SLIDESHTML, $DOCBOOK_DEFAULT_XSL_SLIDESPDF,
           $DOCBOOK_FOP, $DOCBOOK_FOPCOM, $DOCBOOK_FOPFLAGS, $DOCBOOK_XMLLINT,
           $DOCBOOK_XMLLINTCOM, $DOCBOOK_XMLLINTFLAGS, $DOCBOOK_XSLTPROC,
           $DOCBOOK_XSLTPROCCOM, $DOCBOOK_XSLTPROCFLAGS,
           $DOCBOOK_XSLTPROCPARAMS.

           Uses: $DOCBOOK_FOPCOMSTR, $DOCBOOK_XMLLINTCOMSTR,
           $DOCBOOK_XSLTPROCCOMSTR.

       dvi
           Attaches the DVI builder to the construction environment.

       dvipdf
           Sets construction variables for the dvipdf utility.

           Sets: $DVIPDF, $DVIPDFCOM, $DVIPDFFLAGS.

           Uses: $DVIPDFCOMSTR.

       dvips
           Sets construction variables for the dvips utility.

           Sets: $DVIPS, $DVIPSFLAGS, $PSCOM, $PSPREFIX, $PSSUFFIX.

           Uses: $PSCOMSTR.

       f03
           Set construction variables for generic POSIX Fortran 03 compilers.

           Sets: $F03, $F03COM, $F03FLAGS, $F03PPCOM, $SHF03, $SHF03COM,
           $SHF03FLAGS, $SHF03PPCOM, $_F03INCFLAGS.

           Uses: $F03COMSTR, $F03PPCOMSTR, $SHF03COMSTR, $SHF03PPCOMSTR.

       f08
           Set construction variables for generic POSIX Fortran 08 compilers.

           Sets: $F08, $F08COM, $F08FLAGS, $F08PPCOM, $SHF08, $SHF08COM,
           $SHF08FLAGS, $SHF08PPCOM, $_F08INCFLAGS.

           Uses: $F08COMSTR, $F08PPCOMSTR, $SHF08COMSTR, $SHF08PPCOMSTR.

       f77
           Set construction variables for generic POSIX Fortran 77 compilers.

           Sets: $F77, $F77COM, $F77FILESUFFIXES, $F77FLAGS, $F77PPCOM,
           $F77PPFILESUFFIXES, $FORTRAN, $FORTRANCOM, $FORTRANFLAGS, $SHF77,
           $SHF77COM, $SHF77FLAGS, $SHF77PPCOM, $SHFORTRAN, $SHFORTRANCOM,
           $SHFORTRANFLAGS, $SHFORTRANPPCOM, $_F77INCFLAGS.

           Uses: $F77COMSTR, $F77PPCOMSTR, $FORTRANCOMSTR, $FORTRANPPCOMSTR,
           $SHF77COMSTR, $SHF77PPCOMSTR, $SHFORTRANCOMSTR, $SHFORTRANPPCOMSTR.

       f90
           Set construction variables for generic POSIX Fortran 90 compilers.

           Sets: $F90, $F90COM, $F90FLAGS, $F90PPCOM, $SHF90, $SHF90COM,
           $SHF90FLAGS, $SHF90PPCOM, $_F90INCFLAGS.

           Uses: $F90COMSTR, $F90PPCOMSTR, $SHF90COMSTR, $SHF90PPCOMSTR.

       f95
           Set construction variables for generic POSIX Fortran 95 compilers.

           Sets: $F95, $F95COM, $F95FLAGS, $F95PPCOM, $SHF95, $SHF95COM,
           $SHF95FLAGS, $SHF95PPCOM, $_F95INCFLAGS.

           Uses: $F95COMSTR, $F95PPCOMSTR, $SHF95COMSTR, $SHF95PPCOMSTR.

       fortran
           Set construction variables for generic POSIX Fortran compilers.

           Sets: $FORTRAN, $FORTRANCOM, $FORTRANFLAGS, $SHFORTRAN,
           $SHFORTRANCOM, $SHFORTRANFLAGS, $SHFORTRANPPCOM.

           Uses: $FORTRANCOMSTR, $FORTRANPPCOMSTR, $SHFORTRANCOMSTR,
           $SHFORTRANPPCOMSTR.

       g++
           Set construction variables for the gXX C++ compiler.

           Sets: $CXX, $CXXVERSION, $SHCXXFLAGS, $SHOBJSUFFIX.

       g77
           Set construction variables for the g77 Fortran compiler. Calls the
           f77 Tool module to set variables.

       gas
           Sets construction variables for the gas assembler. Calls the as
           module.

           Sets: $AS.

       gcc
           Set construction variables for the gcc C compiler.

           Sets: $CC, $CCVERSION, $SHCCFLAGS.

       gdc
           Sets construction variables for the D language compiler GDC.

           Sets: $DC, $DCOM, $DDEBUG, $DDEBUGPREFIX, $DDEBUGSUFFIX,
           $DFILESUFFIX, $DFLAGPREFIX, $DFLAGS, $DFLAGSUFFIX, $DINCPREFIX,
           $DINCSUFFIX, $DLIB, $DLIBCOM, $DLIBFLAGPREFIX, $DLIBFLAGSUFFIX,
           $DLINK, $DLINKCOM, $DLINKFLAGPREFIX, $DLINKFLAGS, $DLINKFLAGSUFFIX,
           $DPATH, $DVERPREFIX, $DVERSIONS, $DVERSUFFIX, $RPATHPREFIX,
           $RPATHSUFFIX, $SHDC, $SHDCOM, $SHDLINK, $SHDLINKCOM, $SHDLINKFLAGS,
           $_DDEBUGFLAGS, $_DFLAGS, $_DINCFLAGS, $_DLIBFLAGS, $_DVERFLAGS,
           $_RPATH.

       gettext
           This is actually a toolset, which supports internationalization and
           localization of software being constructed with SCons. The toolset
           loads following tools:



           o    xgettext - to extract internationalized messages from source
               code to POT file(s),

           o    msginit - may be optionally used to initialize PO files,

           o    msgmerge - to update PO files, that already contain translated
               messages,

           o    msgfmt - to compile textual PO file to binary installable MO
               file.

           When you enable gettext, it internally loads all abovementioned
           tools, so you're encouraged to see their individual documentation.

           Each of the above tools provides its own builder(s) which may be
           used to perform particular activities related to software
           internationalization. You may be however interested in top-level
           builder Translate described few paragraphs later.

           To use gettext tools add 'gettext' tool to your environment:

                 env = Environment( tools = ['default', 'gettext'] )

       gfortran
           Sets construction variables for the GNU F95/F2003 GNU compiler.

           Sets: $F77, $F90, $F95, $FORTRAN, $SHF77, $SHF77FLAGS, $SHF90,
           $SHF90FLAGS, $SHF95, $SHF95FLAGS, $SHFORTRAN, $SHFORTRANFLAGS.

       gnulink
           Set construction variables for GNU linker/loader.

           Sets: $LDMODULEVERSIONFLAGS, $RPATHPREFIX, $RPATHSUFFIX,
           $SHLIBVERSIONFLAGS, $SHLINKFLAGS, $_LDMODULESONAME, $_SHLIBSONAME.

       gs
           This Tool sets the required construction variables for working with
           the Ghostscript command. It also registers an appropriate Action
           with the PDF Builder (PDF), such that the conversion from PS/EPS to
           PDF happens automatically for the TeX/LaTeX toolchain. Finally, it
           adds an explicit Ghostscript Builder (Gs) to the environment.

           Sets: $GS, $GSCOM, $GSFLAGS.

           Uses: $GSCOMSTR.

       hpc++
           Set construction variables for the compilers aCC on HP/UX systems.

       hpcc
           Set construction variables for the aCC on HP/UX systems. Calls the
           cXX tool for additional variables.

           Sets: $CXX, $CXXVERSION, $SHCXXFLAGS.

       hplink
           Sets construction variables for the linker on HP/UX systems.

           Sets: $LINKFLAGS, $SHLIBSUFFIX, $SHLINKFLAGS.

       icc
           Sets construction variables for the icc compiler on OS/2 systems.

           Sets: $CC, $CCCOM, $CFILESUFFIX, $CPPDEFPREFIX, $CPPDEFSUFFIX,
           $CXXCOM, $CXXFILESUFFIX, $INCPREFIX, $INCSUFFIX.

           Uses: $CCFLAGS, $CFLAGS, $CPPFLAGS, $_CPPDEFFLAGS, $_CPPINCFLAGS.

       icl
           Sets construction variables for the Intel C/C++ compiler. Calls the
           intelc Tool module to set its variables.

       ifl
           Sets construction variables for the Intel Fortran compiler.

           Sets: $FORTRAN, $FORTRANCOM, $FORTRANPPCOM, $SHFORTRANCOM,
           $SHFORTRANPPCOM.

           Uses: $CPPFLAGS, $FORTRANFLAGS, $_CPPDEFFLAGS, $_FORTRANINCFLAGS.

       ifort
           Sets construction variables for newer versions of the Intel Fortran
           compiler for Linux.

           Sets: $F77, $F90, $F95, $FORTRAN, $SHF77, $SHF77FLAGS, $SHF90,
           $SHF90FLAGS, $SHF95, $SHF95FLAGS, $SHFORTRAN, $SHFORTRANFLAGS.

       ilink
           Sets construction variables for the ilink linker on OS/2 systems.

           Sets: $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX,
           $LINK, $LINKCOM, $LINKFLAGS.

       ilink32
           Sets construction variables for the Borland ilink32 linker.

           Sets: $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX,
           $LINK, $LINKCOM, $LINKFLAGS.

       install
           Sets construction variables for file and directory installation.

           Sets: $INSTALL, $INSTALLSTR.

       intelc
           Sets construction variables for the Intel C/C++ compiler (Linux and
           Windows, version 7 and later). Calls the gcc or msvc (on Linux and
           Windows, respectively) to set underlying variables.

           Sets: $AR, $CC, $CXX, $INTEL_C_COMPILER_VERSION, $LINK.

       jar
           Sets construction variables for the jar utility.

           Sets: $JAR, $JARCOM, $JARFLAGS, $JARSUFFIX.

           Uses: $JARCOMSTR.

       javac
           Sets construction variables for the javac compiler.

           Sets: $JAVABOOTCLASSPATH, $JAVAC, $JAVACCOM, $JAVACFLAGS,
           $JAVACLASSPATH, $JAVACLASSSUFFIX, $JAVASOURCEPATH, $JAVASUFFIX.

           Uses: $JAVACCOMSTR.

       javah
           Sets construction variables for the javah tool.

           Sets: $JAVACLASSSUFFIX, $JAVAH, $JAVAHCOM, $JAVAHFLAGS.

           Uses: $JAVACLASSPATH, $JAVAHCOMSTR.

       latex
           Sets construction variables for the latex utility.

           Sets: $LATEX, $LATEXCOM, $LATEXFLAGS.

           Uses: $LATEXCOMSTR.

       ldc
           Sets construction variables for the D language compiler LDC2.

           Sets: $DC, $DCOM, $DDEBUG, $DDEBUGPREFIX, $DDEBUGSUFFIX,
           $DFILESUFFIX, $DFLAGPREFIX, $DFLAGS, $DFLAGSUFFIX, $DINCPREFIX,
           $DINCSUFFIX, $DLIB, $DLIBCOM, $DLIBDIRPREFIX, $DLIBDIRSUFFIX,
           $DLIBFLAGPREFIX, $DLIBFLAGSUFFIX, $DLIBLINKPREFIX, $DLIBLINKSUFFIX,
           $DLINK, $DLINKCOM, $DLINKFLAGPREFIX, $DLINKFLAGS, $DLINKFLAGSUFFIX,
           $DPATH, $DVERPREFIX, $DVERSIONS, $DVERSUFFIX, $RPATHPREFIX,
           $RPATHSUFFIX, $SHDC, $SHDCOM, $SHDLINK, $SHDLINKCOM, $SHDLINKFLAGS,
           $_DDEBUGFLAGS, $_DFLAGS, $_DINCFLAGS, $_DLIBDIRFLAGS, $_DLIBFLAGS,
           $_DLIBFLAGS, $_DVERFLAGS, $_RPATH.

       lex
           Sets construction variables for the lex lexical analyser.

           Sets: $LEX, $LEXCOM, $LEXFLAGS.

           Uses: $LEXCOMSTR.

       link
           Sets construction variables for generic POSIX linkers.

           Sets: $LDMODULE, $LDMODULECOM, $LDMODULEFLAGS,
           $LDMODULENOVERSIONSYMLINKS, $LDMODULEPREFIX, $LDMODULESUFFIX,
           $LDMODULEVERSION, $LDMODULEVERSIONFLAGS, $LIBDIRPREFIX,
           $LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX, $LINK, $LINKCOM,
           $LINKFLAGS, $SHLIBSUFFIX, $SHLINK, $SHLINKCOM, $SHLINKFLAGS,
           $__LDMODULEVERSIONFLAGS, $__SHLIBVERSIONFLAGS.

           Uses: $LDMODULECOMSTR, $LINKCOMSTR, $SHLINKCOMSTR.

       linkloc
           Sets construction variables for the LinkLoc linker for the Phar Lap
           ETS embedded operating system.

           Sets: $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX,
           $LINK, $LINKCOM, $LINKFLAGS, $SHLINK, $SHLINKCOM, $SHLINKFLAGS.

           Uses: $LINKCOMSTR, $SHLINKCOMSTR.

       m4
           Sets construction variables for the m4 macro processor.

           Sets: $M4, $M4COM, $M4FLAGS.

           Uses: $M4COMSTR.

       masm
           Sets construction variables for the Microsoft assembler.

           Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

           Uses: $ASCOMSTR, $ASPPCOMSTR, $CPPFLAGS, $_CPPDEFFLAGS,
           $_CPPINCFLAGS.

       midl
           Sets construction variables for the Microsoft IDL compiler.

           Sets: $MIDL, $MIDLCOM, $MIDLFLAGS.

           Uses: $MIDLCOMSTR.

       mingw
           Sets construction variables for MinGW (Minimal Gnu on Windows).

           Sets: $AS, $CC, $CXX, $LDMODULECOM, $LIBPREFIX, $LIBSUFFIX,
           $OBJSUFFIX, $RC, $RCCOM, $RCFLAGS, $RCINCFLAGS, $RCINCPREFIX,
           $RCINCSUFFIX, $SHCCFLAGS, $SHCXXFLAGS, $SHLINKCOM, $SHLINKFLAGS,
           $SHOBJSUFFIX, $WINDOWSDEFPREFIX, $WINDOWSDEFSUFFIX.

           Uses: $RCCOMSTR, $SHLINKCOMSTR.

       msgfmt
           This scons tool is a part of scons gettext toolset. It provides
           scons interface to msgfmt(1) command, which generates binary
           message catalog (MO) from a textual translation description (PO).

           Sets: $MOSUFFIX, $MSGFMT, $MSGFMTCOM, $MSGFMTCOMSTR, $MSGFMTFLAGS,
           $POSUFFIX.

           Uses: $LINGUAS_FILE.

       msginit
           This scons tool is a part of scons gettext toolset. It provides
           scons interface to msginit(1) program, which creates new PO file,
           initializing the meta information with values from user's
           environment (or options).

           Sets: $MSGINIT, $MSGINITCOM, $MSGINITCOMSTR, $MSGINITFLAGS,
           $POAUTOINIT, $POCREATE_ALIAS, $POSUFFIX, $POTSUFFIX,
           $_MSGINITLOCALE.

           Uses: $LINGUAS_FILE, $POAUTOINIT, $POTDOMAIN.

       msgmerge
           This scons tool is a part of scons gettext toolset. It provides
           scons interface to msgmerge(1) command, which merges two Uniform
           style .po files together.

           Sets: $MSGMERGE, $MSGMERGECOM, $MSGMERGECOMSTR, $MSGMERGEFLAGS,
           $POSUFFIX, $POTSUFFIX, $POUPDATE_ALIAS.

           Uses: $LINGUAS_FILE, $POAUTOINIT, $POTDOMAIN.

       mslib
           Sets construction variables for the Microsoft mslib library
           archiver.

           Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX.

           Uses: $ARCOMSTR.

       mslink
           Sets construction variables for the Microsoft linker.

           Sets: $LDMODULE, $LDMODULECOM, $LDMODULEFLAGS, $LDMODULEPREFIX,
           $LDMODULESUFFIX, $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX,
           $LIBLINKSUFFIX, $LINK, $LINKCOM, $LINKFLAGS, $REGSVR, $REGSVRCOM,
           $REGSVRFLAGS, $SHLINK, $SHLINKCOM, $SHLINKFLAGS, $WIN32DEFPREFIX,
           $WIN32DEFSUFFIX, $WIN32EXPPREFIX, $WIN32EXPSUFFIX,
           $WINDOWSDEFPREFIX, $WINDOWSDEFSUFFIX, $WINDOWSEXPPREFIX,
           $WINDOWSEXPSUFFIX, $WINDOWSPROGMANIFESTPREFIX,
           $WINDOWSPROGMANIFESTSUFFIX, $WINDOWSSHLIBMANIFESTPREFIX,
           $WINDOWSSHLIBMANIFESTSUFFIX, $WINDOWS_INSERT_DEF.

           Uses: $LDMODULECOMSTR, $LINKCOMSTR, $REGSVRCOMSTR, $SHLINKCOMSTR.

       mssdk
           Sets variables for Microsoft Platform SDK and/or Windows SDK. Note
           that unlike most other Tool modules, mssdk does not set
           construction variables, but sets the environment variables in the
           environment SCons uses to execute the Microsoft toolchain:
           %INCLUDE%, %LIB%, %LIBPATH% and %PATH%.

           Uses: $MSSDK_DIR, $MSSDK_VERSION, $MSVS_VERSION.

       msvc
           Sets construction variables for the Microsoft Visual C/C++
           compiler.

           Sets: $BUILDERS, $CC, $CCCOM, $CCFLAGS, $CCPCHFLAGS, $CCPDBFLAGS,
           $CFILESUFFIX, $CFLAGS, $CPPDEFPREFIX, $CPPDEFSUFFIX, $CXX, $CXXCOM,
           $CXXFILESUFFIX, $CXXFLAGS, $INCPREFIX, $INCSUFFIX, $OBJPREFIX,
           $OBJSUFFIX, $PCHCOM, $PCHPDBFLAGS, $RC, $RCCOM, $RCFLAGS, $SHCC,
           $SHCCCOM, $SHCCFLAGS, $SHCFLAGS, $SHCXX, $SHCXXCOM, $SHCXXFLAGS,
           $SHOBJPREFIX, $SHOBJSUFFIX.

           Uses: $CCCOMSTR, $CXXCOMSTR, $PCH, $PCHSTOP, $PDB, $SHCCCOMSTR,
           $SHCXXCOMSTR.

       msvs
           Sets construction variables for Microsoft Visual Studio.

           Sets: $MSVSBUILDCOM, $MSVSCLEANCOM, $MSVSENCODING, $MSVSPROJECTCOM,
           $MSVSREBUILDCOM, $MSVSSCONS, $MSVSSCONSCOM, $MSVSSCONSCRIPT,
           $MSVSSCONSFLAGS, $MSVSSOLUTIONCOM.

       mwcc
           Sets construction variables for the Metrowerks CodeWarrior
           compiler.

           Sets: $CC, $CCCOM, $CFILESUFFIX, $CPPDEFPREFIX, $CPPDEFSUFFIX,
           $CXX, $CXXCOM, $CXXFILESUFFIX, $INCPREFIX, $INCSUFFIX,
           $MWCW_VERSION, $MWCW_VERSIONS, $SHCC, $SHCCCOM, $SHCCFLAGS,
           $SHCFLAGS, $SHCXX, $SHCXXCOM, $SHCXXFLAGS.

           Uses: $CCCOMSTR, $CXXCOMSTR, $SHCCCOMSTR, $SHCXXCOMSTR.

       mwld
           Sets construction variables for the Metrowerks CodeWarrior linker.

           Sets: $AR, $ARCOM, $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX,
           $LIBLINKSUFFIX, $LINK, $LINKCOM, $SHLINK, $SHLINKCOM, $SHLINKFLAGS.

       nasm
           Sets construction variables for the nasm Netwide Assembler.

           Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

           Uses: $ASCOMSTR, $ASPPCOMSTR.

       packaging
           A framework for building binary and source packages.

       Packaging
           Sets construction variables for the Package Builder.

       pdf
           Sets construction variables for the Portable Document Format
           builder.

           Sets: $PDFPREFIX, $PDFSUFFIX.

       pdflatex
           Sets construction variables for the pdflatex utility.

           Sets: $LATEXRETRIES, $PDFLATEX, $PDFLATEXCOM, $PDFLATEXFLAGS.

           Uses: $PDFLATEXCOMSTR.

       pdftex
           Sets construction variables for the pdftex utility.

           Sets: $LATEXRETRIES, $PDFLATEX, $PDFLATEXCOM, $PDFLATEXFLAGS,
           $PDFTEX, $PDFTEXCOM, $PDFTEXFLAGS.

           Uses: $PDFLATEXCOMSTR, $PDFTEXCOMSTR.

       Perforce
           Sets construction variables for interacting with the Perforce
           source code management system.

           Sets: $P4, $P4COM, $P4FLAGS.

           Uses: $P4COMSTR.

       qt
           Sets construction variables for building Qt applications.

           Sets: $QTDIR, $QT_AUTOSCAN, $QT_BINPATH, $QT_CPPPATH, $QT_LIB,
           $QT_LIBPATH, $QT_MOC, $QT_MOCCXXPREFIX, $QT_MOCCXXSUFFIX,
           $QT_MOCFROMCXXCOM, $QT_MOCFROMCXXFLAGS, $QT_MOCFROMHCOM,
           $QT_MOCFROMHFLAGS, $QT_MOCHPREFIX, $QT_MOCHSUFFIX, $QT_UIC,
           $QT_UICCOM, $QT_UICDECLFLAGS, $QT_UICDECLPREFIX, $QT_UICDECLSUFFIX,
           $QT_UICIMPLFLAGS, $QT_UICIMPLPREFIX, $QT_UICIMPLSUFFIX,
           $QT_UISUFFIX.

       RCS
           Sets construction variables for the interaction with the Revision
           Control System.

           Sets: $RCS, $RCS_CO, $RCS_COCOM, $RCS_COFLAGS.

           Uses: $RCS_COCOMSTR.

       rmic
           Sets construction variables for the rmic utility.

           Sets: $JAVACLASSSUFFIX, $RMIC, $RMICCOM, $RMICFLAGS.

           Uses: $RMICCOMSTR.

       rpcgen
           Sets construction variables for building with RPCGEN.

           Sets: $RPCGEN, $RPCGENCLIENTFLAGS, $RPCGENFLAGS,
           $RPCGENHEADERFLAGS, $RPCGENSERVICEFLAGS, $RPCGENXDRFLAGS.

       SCCS
           Sets construction variables for interacting with the Source Code
           Control System.

           Sets: $SCCS, $SCCSCOM, $SCCSFLAGS, $SCCSGETFLAGS.

           Uses: $SCCSCOMSTR.

       sgiar
           Sets construction variables for the SGI library archiver.

           Sets: $AR, $ARCOMSTR, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX, $SHLINK,
           $SHLINKFLAGS.

           Uses: $ARCOMSTR, $SHLINKCOMSTR.

       sgic++
           Sets construction variables for the SGI C++ compiler.

           Sets: $CXX, $CXXFLAGS, $SHCXX, $SHOBJSUFFIX.

       sgicc
           Sets construction variables for the SGI C compiler.

           Sets: $CXX, $SHOBJSUFFIX.

       sgilink
           Sets construction variables for the SGI linker.

           Sets: $LINK, $RPATHPREFIX, $RPATHSUFFIX, $SHLINKFLAGS.

       sunar
           Sets construction variables for the Sun library archiver.

           Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX.

           Uses: $ARCOMSTR.

       sunc++
           Sets construction variables for the Sun C++ compiler.

           Sets: $CXX, $CXXVERSION, $SHCXX, $SHCXXFLAGS, $SHOBJPREFIX,
           $SHOBJSUFFIX.

       suncc
           Sets construction variables for the Sun C compiler.

           Sets: $CXX, $SHCCFLAGS, $SHOBJPREFIX, $SHOBJSUFFIX.

       sunf77
           Set construction variables for the Sun f77 Fortran compiler.

           Sets: $F77, $FORTRAN, $SHF77, $SHF77FLAGS, $SHFORTRAN,
           $SHFORTRANFLAGS.

       sunf90
           Set construction variables for the Sun f90 Fortran compiler.

           Sets: $F90, $FORTRAN, $SHF90, $SHF90FLAGS, $SHFORTRAN,
           $SHFORTRANFLAGS.

       sunf95
           Set construction variables for the Sun f95 Fortran compiler.

           Sets: $F95, $FORTRAN, $SHF95, $SHF95FLAGS, $SHFORTRAN,
           $SHFORTRANFLAGS.

       sunlink
           Sets construction variables for the Sun linker.

           Sets: $RPATHPREFIX, $RPATHSUFFIX, $SHLINKFLAGS.

       swig
           Sets construction variables for the SWIG interface generator.

           Sets: $SWIG, $SWIGCFILESUFFIX, $SWIGCOM, $SWIGCXXFILESUFFIX,
           $SWIGDIRECTORSUFFIX, $SWIGFLAGS, $SWIGINCPREFIX, $SWIGINCSUFFIX,
           $SWIGPATH, $SWIGVERSION, $_SWIGINCFLAGS.

           Uses: $SWIGCOMSTR.

       tar
           Sets construction variables for the tar archiver.

           Sets: $TAR, $TARCOM, $TARFLAGS, $TARSUFFIX.

           Uses: $TARCOMSTR.

       tex
           Sets construction variables for the TeX formatter and typesetter.

           Sets: $BIBTEX, $BIBTEXCOM, $BIBTEXFLAGS, $LATEX, $LATEXCOM,
           $LATEXFLAGS, $MAKEINDEX, $MAKEINDEXCOM, $MAKEINDEXFLAGS, $TEX,
           $TEXCOM, $TEXFLAGS.

           Uses: $BIBTEXCOMSTR, $LATEXCOMSTR, $MAKEINDEXCOMSTR, $TEXCOMSTR.

       textfile
           Set construction variables for the Textfile and Substfile builders.

           Sets: $LINESEPARATOR, $SUBSTFILEPREFIX, $SUBSTFILESUFFIX,
           $TEXTFILEPREFIX, $TEXTFILESUFFIX.

           Uses: $SUBST_DICT.

       tlib
           Sets construction variables for the Borlan tib library archiver.

           Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX.

           Uses: $ARCOMSTR.

       xgettext
           This scons tool is a part of scons gettext toolset. It provides
           scons interface to xgettext(1) program, which extracts
           internationalized messages from source code. The tool provides
           POTUpdate builder to make PO Template files.

           Sets: $POTSUFFIX, $POTUPDATE_ALIAS, $XGETTEXTCOM, $XGETTEXTCOMSTR,
           $XGETTEXTFLAGS, $XGETTEXTFROM, $XGETTEXTFROMPREFIX,
           $XGETTEXTFROMSUFFIX, $XGETTEXTPATH, $XGETTEXTPATHPREFIX,
           $XGETTEXTPATHSUFFIX, $_XGETTEXTDOMAIN, $_XGETTEXTFROMFLAGS,
           $_XGETTEXTPATHFLAGS.

           Uses: $POTDOMAIN.

       yacc
           Sets construction variables for the yacc parse generator.

           Sets: $YACC, $YACCCOM, $YACCFLAGS, $YACCHFILESUFFIX,
           $YACCHXXFILESUFFIX, $YACCVCGFILESUFFIX.

           Uses: $YACCCOMSTR.

       zip
           Sets construction variables for the zip archiver.

           Sets: $ZIP, $ZIPCOM, $ZIPCOMPRESSION, $ZIPFLAGS, $ZIPSUFFIX.

           Uses: $ZIPCOMSTR.

       Additionally, there is a "tool" named default which configures the
       environment with a default set of tools for the current platform.

       On posix and cygwin platforms the GNU tools (e.g. gcc) are preferred by
       SCons, on Windows the Microsoft tools (e.g. msvc) followed by MinGW are
       preferred by SCons, and in OS/2 the IBM tools (e.g. icc) are preferred
       by SCons.

   Builder Methods
       Build rules are specified by calling a construction environment's
       builder methods. The arguments to the builder methods are target (a
       list of targets to be built, usually file names) and source (a list of
       sources to be built, usually file names).

       Because long lists of file names can lead to a lot of quoting, scons
       supplies a Split() global function and a same-named environment method
       that split a single string into a list, separated on strings of
       white-space characters. (These are similar to the split() member
       function of Python strings but work even if the input isn't a string.)

       Like all Python arguments, the target and source arguments to a builder
       method can be specified either with or without the "target" and
       "source" keywords. When the keywords are omitted, the target is first,
       followed by the source. The following are equivalent examples of
       calling the Program builder method:

           env.Program('bar', ['bar.c', 'foo.c'])
           env.Program('bar', Split('bar.c foo.c'))
           env.Program('bar', env.Split('bar.c foo.c'))
           env.Program(source =  ['bar.c', 'foo.c'], target = 'bar')
           env.Program(target = 'bar', Split('bar.c foo.c'))
           env.Program(target = 'bar', env.Split('bar.c foo.c'))
           env.Program('bar', source = 'bar.c foo.c'.split())

       Target and source file names that are not absolute path names (that is,
       do not begin with / on POSIX systems or \fR on Windows systems, with or
       without an optional drive letter) are interpreted relative to the
       directory containing the SConscript file being read. An initial # (hash
       mark) on a path name means that the rest of the file name is
       interpreted relative to the directory containing the top-level
       SConstruct file, even if the # is followed by a directory separator
       character (slash or backslash).

       Examples:

           # The comments describing the targets that will be built
           # assume these calls are in a SConscript file in the
           # a subdirectory named "subdir".

           # Builds the program "subdir/foo" from "subdir/foo.c":
           env.Program('foo', 'foo.c')

           # Builds the program "/tmp/bar" from "subdir/bar.c":
           env.Program('/tmp/bar', 'bar.c')

           # An initial '#' or '#/' are equivalent; the following
           # calls build the programs "foo" and "bar" (in the
           # top-level SConstruct directory) from "subdir/foo.c" and
           # "subdir/bar.c", respectively:
           env.Program('#foo', 'foo.c')
           env.Program('#/bar', 'bar.c')

           # Builds the program "other/foo" (relative to the top-level
           # SConstruct directory) from "subdir/foo.c":
           env.Program('#other/foo', 'foo.c')

       When the target shares the same base name as the source and only the
       suffix varies, and if the builder method has a suffix defined for the
       target file type, then the target argument may be omitted completely,
       and scons will deduce the target file name from the source file name.
       The following examples all build the executable program bar (on POSIX
       systems) or bar.exe (on Windows systems) from the bar.c source file:

           env.Program(target = 'bar', source = 'bar.c')
           env.Program('bar', source = 'bar.c')
           env.Program(source = 'bar.c')
           env.Program('bar.c')

       As a convenience, a srcdir keyword argument may be specified when
       calling a Builder. When specified, all source file strings that are not
       absolute paths will be interpreted relative to the specified srcdir.
       The following example will build the build/prog (or build/prog.exe on
       Windows) program from the files src/f1.c and src/f2.c:

           env.Program('build/prog', ['f1.c', 'f2.c'], srcdir='src')

       It is possible to override or add construction variables when calling a
       builder method by passing additional keyword arguments. These
       overridden or added variables will only be in effect when building the
       target, so they will not affect other parts of the build. For example,
       if you want to add additional libraries for just one program:

           env.Program('hello', 'hello.c', LIBS=['gl', 'glut'])

       or generate a shared library with a non-standard suffix:

           env.SharedLibrary('word', 'word.cpp',
                             SHLIBSUFFIX='.ocx',
                             LIBSUFFIXES=['.ocx'])

       (Note that both the $SHLIBSUFFIX and $LIBSUFFIXES variables must be set
       if you want SCons to search automatically for dependencies on the
       non-standard library names; see the descriptions of these variables,
       below, for more information.)

       It is also possible to use the parse_flags keyword argument in an
       override:

           env = Program('hello', 'hello.c', parse_flags = '-Iinclude -DEBUG -lm')

       This example adds 'include' to CPPPATH, 'EBUG' to CPPDEFINES, and 'm'
       to LIBS.

       Although the builder methods defined by scons are, in fact, methods of
       a construction environment object, they may also be called without an
       explicit environment:

           Program('hello', 'hello.c')
           SharedLibrary('word', 'word.cpp')

       In this case, the methods are called internally using a default
       construction environment that consists of the tools and values that
       scons has determined are appropriate for the local system.

       Builder methods that can be called without an explicit environment may
       be called from custom Python modules that you import into an SConscript
       file by adding the following to the Python module:

           from SCons.Script import *

       All builder methods return a list-like object containing Nodes that
       represent the target or targets that will be built. A Node is an
       internal SCons object which represents build targets or sources.

       The returned Node-list object can be passed to other builder methods as
       source(s) or passed to any SCons function or method where a filename
       would normally be accepted. For example, if it were necessary to add a
       specific -D flag when compiling one specific object file:

           bar_obj_list = env.StaticObject('bar.c', CPPDEFINES='-DBAR')
           env.Program(source = ['foo.c', bar_obj_list, 'main.c'])

       Using a Node in this way makes for a more portable build by avoiding
       having to specify a platform-specific object suffix when calling the
       Program() builder method.

       Note that Builder calls will automatically "flatten" the source and
       target file lists, so it's all right to have the bar_obj list return by
       the StaticObject() call in the middle of the source file list. If you
       need to manipulate a list of lists returned by Builders directly using
       Python, you can either build the list by hand:

           foo = Object('foo.c')
           bar = Object('bar.c')
           objects = ['begin.o'] + foo + ['middle.o'] + bar + ['end.o']
           for object in objects:
               print str(object)

       Or you can use the Flatten() function supplied by scons to create a
       list containing just the Nodes, which may be more convenient:

           foo = Object('foo.c')
           bar = Object('bar.c')
           objects = Flatten(['begin.o', foo, 'middle.o', bar, 'end.o'])
           for object in objects:
               print str(object)

       Note also that because Builder calls return a list-like object, not an
       actual Python list, you should not use the Python += operator to append
       Builder results to a Python list. Because the list and the object are
       different types, Python will not update the original list in place, but
       will instead create a new Node-list object containing the concatenation
       of the list elements and the Builder results. This will cause problems
       for any other Python variables in your SCons configuration that still
       hold on to a reference to the original list. Instead, use the Python
       .extend() method to make sure the list is updated in-place. Example:

           object_files = []

           # Do NOT use += as follows:
           #
           #    object_files += Object('bar.c')
           #
           # It will not update the object_files list in place.
           #
           # Instead, use the .extend() method:
           object_files.extend(Object('bar.c'))


       The path name for a Node's file may be used by passing the Node to the
       Python-builtin str() function:

           bar_obj_list = env.StaticObject('bar.c', CPPDEFINES='-DBAR')
           print "The path to bar_obj is:", str(bar_obj_list[0])

       Note again that because the Builder call returns a list, we have to
       access the first element in the list (bar_obj_list[0]) to get at the
       Node that actually represents the object file.

       Builder calls support a chdir keyword argument that specifies that the
       Builder's action(s) should be executed after changing directory. If the
       chdir argument is a string or a directory Node, scons will change to
       the specified directory. If the chdir is not a string or Node and is
       non-zero, then scons will change to the target file's directory.

           # scons will change to the "sub" subdirectory
           # before executing the "cp" command.
           env.Command('sub/dir/foo.out', 'sub/dir/foo.in',
                       "cp dir/foo.in dir/foo.out",
                       chdir='sub')

           # Because chdir is not a string, scons will change to the
           # target's directory ("sub/dir") before executing the
           # "cp" command.
           env.Command('sub/dir/foo.out', 'sub/dir/foo.in',
                       "cp foo.in foo.out",
                       chdir=1)

       Note that scons will not automatically modify its expansion of
       construction variables like $TARGET and $SOURCE when using the chdir
       keyword argument--that is, the expanded file names will still be
       relative to the top-level SConstruct directory, and consequently
       incorrect relative to the chdir directory. If you use the chdir keyword
       argument, you will typically need to supply a different command line
       using expansions like ${TARGET.file} and ${SOURCE.file} to use just the
       filename portion of the targets and source.

       scons provides the following builder methods:

       CFile(), env.CFile()
           Builds a C source file given a lex (.l) or yacc (.y) input file.
           The suffix specified by the $CFILESUFFIX construction variable (.c
           by default) is automatically added to the target if it is not
           already present. Example:

               # builds foo.c
               env.CFile(target = 'foo.c', source = 'foo.l')
               # builds bar.c
               env.CFile(target = 'bar', source = 'bar.y')

       Command(), env.Command()
           The Command "Builder" is actually implemented as a function that
           looks like a Builder, but actually takes an additional argument of
           the action from which the Builder should be made. See the Command
           function description for the calling syntax and details.

       CXXFile(), env.CXXFile()
           Builds a C++ source file given a lex (.ll) or yacc (.yy) input
           file. The suffix specified by the $CXXFILESUFFIX construction
           variable (.cc by default) is automatically added to the target if
           it is not already present. Example:

               # builds foo.cc
               env.CXXFile(target = 'foo.cc', source = 'foo.ll')
               # builds bar.cc
               env.CXXFile(target = 'bar', source = 'bar.yy')

       DocbookEpub(), env.DocbookEpub()
           A pseudo-Builder, providing a Docbook toolchain for EPUB output.

               env = Environment(tools=['docbook'])
               env.DocbookEpub('manual.epub', 'manual.xml')

           or simply

               env = Environment(tools=['docbook'])
               env.DocbookEpub('manual')

       DocbookHtml(), env.DocbookHtml()
           A pseudo-Builder, providing a Docbook toolchain for HTML output.

               env = Environment(tools=['docbook'])
               env.DocbookHtml('manual.html', 'manual.xml')

           or simply

               env = Environment(tools=['docbook'])
               env.DocbookHtml('manual')

       DocbookHtmlChunked(), env.DocbookHtmlChunked()
           A pseudo-Builder, providing a Docbook toolchain for chunked HTML
           output. It supports the base.dir parameter. The chunkfast.xsl file
           (requires "EXSLT") is used as the default stylesheet. Basic syntax:

               env = Environment(tools=['docbook'])
               env.DocbookHtmlChunked('manual')

           where manual.xml is the input file.

           If you use the root.filename parameter in your own stylesheets you
           have to specify the new target name. This ensures that the
           dependencies get correct, especially for the cleanup via "scons
           -c":

               env = Environment(tools=['docbook'])
               env.DocbookHtmlChunked('mymanual.html', 'manual', xsl='htmlchunk.xsl')

           Some basic support for the base.dir is provided. You can add the
           base_dir keyword to your Builder call, and the given prefix gets
           prepended to all the created filenames:

               env = Environment(tools=['docbook'])
               env.DocbookHtmlChunked('manual', xsl='htmlchunk.xsl', base_dir='output/')

           Make sure that you don't forget the trailing slash for the base
           folder, else your files get renamed only!

       DocbookHtmlhelp(), env.DocbookHtmlhelp()
           A pseudo-Builder, providing a Docbook toolchain for HTMLHELP
           output. Its basic syntax is:

               env = Environment(tools=['docbook'])
               env.DocbookHtmlhelp('manual')

           where manual.xml is the input file.

           If you use the root.filename parameter in your own stylesheets you
           have to specify the new target name. This ensures that the
           dependencies get correct, especially for the cleanup via "scons
           -c":

               env = Environment(tools=['docbook'])
               env.DocbookHtmlhelp('mymanual.html', 'manual', xsl='htmlhelp.xsl')

           Some basic support for the base.dir parameter is provided. You can
           add the base_dir keyword to your Builder call, and the given prefix
           gets prepended to all the created filenames:

               env = Environment(tools=['docbook'])
               env.DocbookHtmlhelp('manual', xsl='htmlhelp.xsl', base_dir='output/')

           Make sure that you don't forget the trailing slash for the base
           folder, else your files get renamed only!

       DocbookMan(), env.DocbookMan()
           A pseudo-Builder, providing a Docbook toolchain for Man page
           output. Its basic syntax is:

               env = Environment(tools=['docbook'])
               env.DocbookMan('manual')

           where manual.xml is the input file. Note, that you can specify a
           target name, but the actual output names are automatically set from
           the refname entries in your XML source.

       DocbookPdf(), env.DocbookPdf()
           A pseudo-Builder, providing a Docbook toolchain for PDF output.

               env = Environment(tools=['docbook'])
               env.DocbookPdf('manual.pdf', 'manual.xml')

           or simply

               env = Environment(tools=['docbook'])
               env.DocbookPdf('manual')

       DocbookSlidesHtml(), env.DocbookSlidesHtml()
           A pseudo-Builder, providing a Docbook toolchain for HTML slides
           output.

               env = Environment(tools=['docbook'])
               env.DocbookSlidesHtml('manual')

           If you use the titlefoil.html parameter in your own stylesheets you
           have to give the new target name. This ensures that the
           dependencies get correct, especially for the cleanup via "scons
           -c":

               env = Environment(tools=['docbook'])
               env.DocbookSlidesHtml('mymanual.html','manual', xsl='slideshtml.xsl')

           Some basic support for the base.dir parameter is provided. You can
           add the base_dir keyword to your Builder call, and the given prefix
           gets prepended to all the created filenames:

               env = Environment(tools=['docbook'])
               env.DocbookSlidesHtml('manual', xsl='slideshtml.xsl', base_dir='output/')

           Make sure that you don't forget the trailing slash for the base
           folder, else your files get renamed only!

       DocbookSlidesPdf(), env.DocbookSlidesPdf()
           A pseudo-Builder, providing a Docbook toolchain for PDF slides
           output.

               env = Environment(tools=['docbook'])
               env.DocbookSlidesPdf('manual.pdf', 'manual.xml')

           or simply

               env = Environment(tools=['docbook'])
               env.DocbookSlidesPdf('manual')

       DocbookXInclude(), env.DocbookXInclude()
           A pseudo-Builder, for resolving XIncludes in a separate processing
           step.

               env = Environment(tools=['docbook'])
               env.DocbookXInclude('manual_xincluded.xml', 'manual.xml')

       DocbookXslt(), env.DocbookXslt()
           A pseudo-Builder, applying a given XSL transformation to the input
           file.

               env = Environment(tools=['docbook'])
               env.DocbookXslt('manual_transformed.xml', 'manual.xml', xsl='transform.xslt')

           Note, that this builder requires the xsl parameter to be set.

       DVI(), env.DVI()
           Builds a .dvi file from a .tex, .ltx or .latex input file. If the
           source file suffix is .tex, scons will examine the contents of the
           file; if the string \documentclass or \documentstyle is found, the
           file is assumed to be a LaTeX file and the target is built by
           invoking the $LATEXCOM command line; otherwise, the $TEXCOM command
           line is used. If the file is a LaTeX file, the DVI builder method
           will also examine the contents of the .aux file and invoke the
           $BIBTEX command line if the string bibdata is found, start
           $MAKEINDEX to generate an index if a .ind file is found and will
           examine the contents .log file and re-run the $LATEXCOM command if
           the log file says it is necessary.

           The suffix .dvi (hard-coded within TeX itself) is automatically
           added to the target if it is not already present. Examples:

               # builds from aaa.tex
               env.DVI(target = 'aaa.dvi', source = 'aaa.tex')
               # builds bbb.dvi
               env.DVI(target = 'bbb', source = 'bbb.ltx')
               # builds from ccc.latex
               env.DVI(target = 'ccc.dvi', source = 'ccc.latex')

       Gs(), env.Gs()
           A Builder for explicitly calling the gs executable. Depending on
           the underlying OS, the different names gs, gsos2 and gswin32c are
           tried.

               env = Environment(tools=['gs'])
               env.Gs('cover.jpg','scons-scons.pdf',
                      GSFLAGS='-dNOPAUSE -dBATCH -sDEVICE=jpeg -dFirstPage=1 -dLastPage=1 -q')
                      )

       Install(), env.Install()
           Installs one or more source files or directories in the specified
           target, which must be a directory. The names of the specified
           source files or directories remain the same within the destination
           directory. The sources may be given as a string or as a node
           returned by a builder.

               env.Install('/usr/local/bin', source = ['foo', 'bar'])

       InstallAs(), env.InstallAs()
           Installs one or more source files or directories to specific names,
           allowing changing a file or directory name as part of the
           installation. It is an error if the target and source arguments
           list different numbers of files or directories.

               env.InstallAs(target = '/usr/local/bin/foo',
                             source = 'foo_debug')
               env.InstallAs(target = ['../lib/libfoo.a', '../lib/libbar.a'],
                             source = ['libFOO.a', 'libBAR.a'])

       InstallVersionedLib(), env.InstallVersionedLib()
           Installs a versioned shared library. The symlinks appropriate to
           the architecture will be generated based on symlinks of the source
           library.

               env.InstallVersionedLib(target = '/usr/local/bin/foo',
                             source = 'libxyz.1.5.2.so')

       Jar(), env.Jar()
           Builds a Java archive (.jar) file from the specified list of
           sources. Any directories in the source list will be searched for
           .class files). Any .java files in the source list will be compiled
           to .class files by calling the Java Builder.

           If the $JARCHDIR value is set, the jar command will change to the
           specified directory using the -C option. If $JARCHDIR is not set
           explicitly, SCons will use the top of any subdirectory tree in
           which Java .class were built by the Java Builder.

           If the contents any of the source files begin with the string
           Manifest-Version, the file is assumed to be a manifest and is
           passed to the jar command with the m option set.

               env.Jar(target = 'foo.jar', source = 'classes')

               env.Jar(target = 'bar.jar',
                       source = ['bar1.java', 'bar2.java'])

       Java(), env.Java()
           Builds one or more Java class files. The sources may be any
           combination of explicit .java files, or directory trees which will
           be scanned for .java files.

           SCons will parse each source .java file to find the classes
           (including inner classes) defined within that file, and from that
           figure out the target .class files that will be created. The class
           files will be placed underneath the specified target directory.

           SCons will also search each Java file for the Java package name,
           which it assumes can be found on a line beginning with the string
           package in the first column; the resulting .class files will be
           placed in a directory reflecting the specified package name. For
           example, the file Foo.java defining a single public Foo class and
           containing a package name of sub.dir will generate a corresponding
           sub/dir/Foo.class class file.

           Examples:

               env.Java(target = 'classes', source = 'src')
               env.Java(target = 'classes', source = ['src1', 'src2'])
               env.Java(target = 'classes', source = ['File1.java', 'File2.java'])

           Java source files can use the native encoding for the underlying
           OS. Since SCons compiles in simple ASCII mode by default, the
           compiler will generate warnings about unmappable characters, which
           may lead to errors as the file is processed further. In this case,
           the user must specify the LANG environment variable to tell the
           compiler what encoding is used. For portibility, it's best if the
           encoding is hard-coded so that the compile will work if it is done
           on a system with a different encoding.

               env = Environment()
               env['ENV']['LANG'] = 'en_GB.UTF-8'

       JavaH(), env.JavaH()
           Builds C header and source files for implementing Java native
           methods. The target can be either a directory in which the header
           files will be written, or a header file name which will contain all
           of the definitions. The source can be the names of .class files,
           the names of .java files to be compiled into .class files by
           calling the Java builder method, or the objects returned from the
           Java builder method.

           If the construction variable $JAVACLASSDIR is set, either in the
           environment or in the call to the JavaH builder method itself, then
           the value of the variable will be stripped from the beginning of
           any .class file names.

           Examples:

               # builds java_native.h
               classes = env.Java(target = 'classdir', source = 'src')
               env.JavaH(target = 'java_native.h', source = classes)

               # builds include/package_foo.h and include/package_bar.h
               env.JavaH(target = 'include',
                         source = ['package/foo.class', 'package/bar.class'])

               # builds export/foo.h and export/bar.h
               env.JavaH(target = 'export',
                         source = ['classes/foo.class', 'classes/bar.class'],
                         JAVACLASSDIR = 'classes')

       Library(), env.Library()
           A synonym for the StaticLibrary builder method.

       LoadableModule(), env.LoadableModule()
           On most systems, this is the same as SharedLibrary. On Mac OS X
           (Darwin) platforms, this creates a loadable module bundle.

       M4(), env.M4()
           Builds an output file from an M4 input file. This uses a default
           $M4FLAGS value of -E, which considers all warnings to be fatal and
           stops on the first warning when using the GNU version of m4.
           Example:

               env.M4(target = 'foo.c', source = 'foo.c.m4')

       Moc(), env.Moc()
           Builds an output file from a moc input file. Moc input files are
           either header files or cxx files. This builder is only available
           after using the tool 'qt'. See the $QTDIR variable for more
           information. Example:

               env.Moc('foo.h') # generates moc_foo.cc
               env.Moc('foo.cpp') # generates foo.moc

       MOFiles(), env.MOFiles()
           This builder belongs to msgfmt tool. The builder compiles PO files
           to MO files.


           Example 1. Create pl.mo and en.mo by compiling pl.po and en.po:

                 # ...
                 env.MOFiles(['pl', 'en'])


           Example 2. Compile files for languages defined in LINGUAS file:

                 # ...
                 env.MOFiles(LINGUAS_FILE = 1)


           Example 3. Create pl.mo and en.mo by compiling pl.po and en.po plus
           files for languages defined in LINGUAS file:

                 # ...
                 env.MOFiles(['pl', 'en'], LINGUAS_FILE = 1)


           Example 4. Compile files for languages defined in LINGUAS file
           (another version):

                 # ...
                 env['LINGUAS_FILE'] = 1
                 env.MOFiles()

       MSVSProject(), env.MSVSProject()
           Builds a Microsoft Visual Studio project file, and by default
           builds a solution file as well.

           This builds a Visual Studio project file, based on the version of
           Visual Studio that is configured (either the latest installed
           version, or the version specified by $MSVS_VERSION in the
           Environment constructor). For Visual Studio 6, it will generate a
           .dsp file. For Visual Studio 7 (.NET) and later versions, it will
           generate a .vcproj file.

           By default, this also generates a solution file for the specified
           project, a .dsw file for Visual Studio 6 or a .sln file for Visual
           Studio 7 (.NET). This behavior may be disabled by specifying
           auto_build_solution=0 when you call MSVSProject, in which case you
           presumably want to build the solution file(s) by calling the
           MSVSSolution Builder (see below).

           The MSVSProject builder takes several lists of filenames to be
           placed into the project file. These are currently limited to srcs,
           incs, localincs, resources, and misc. These are pretty
           self-explanatory, but it should be noted that these lists are added
           to the $SOURCES construction variable as strings, NOT as SCons File
           Nodes. This is because they represent file names to be added to the
           project file, not the source files used to build the project file.

           The above filename lists are all optional, although at least one
           must be specified for the resulting project file to be non-empty.

           In addition to the above lists of values, the following values may
           be specified:

           target
               The name of the target .dsp or .vcproj file. The correct suffix
               for the version of Visual Studio must be used, but the
               $MSVSPROJECTSUFFIX construction variable will be defined to the
               correct value (see example below).

           variant
               The name of this particular variant. For Visual Studio 7
               projects, this can also be a list of variant names. These are
               typically things like "Debug" or "Release", but really can be
               anything you want. For Visual Studio 7 projects, they may also
               specify a target platform separated from the variant name by a
               | (vertical pipe) character: Debug|Xbox. The default target
               platform is Win32. Multiple calls to MSVSProject with different
               variants are allowed; all variants will be added to the project
               file with their appropriate build targets and sources.

           cmdargs
               Additional command line arguments for the different variants.
               The number of cmdargs entries must match the number of variant
               entries, or be empty (not specified). If you give only one, it
               will automatically be propagated to all variants.

           buildtarget
               An optional string, node, or list of strings or nodes (one per
               build variant), to tell the Visual Studio debugger what output
               target to use in what build variant. The number of buildtarget
               entries must match the number of variant entries.

           runfile
               The name of the file that Visual Studio 7 and later will run
               and debug. This appears as the value of the Output field in the
               resulting Visual Studio project file. If this is not specified,
               the default is the same as the specified buildtarget value.

           Note that because SCons always executes its build commands from the
           directory in which the SConstruct file is located, if you generate
           a project file in a different directory than the SConstruct
           directory, users will not be able to double-click on the file name
           in compilation error messages displayed in the Visual Studio
           console output window. This can be remedied by adding the Visual
           C/C++ /FC compiler option to the $CCFLAGS variable so that the
           compiler will print the full path name of any files that cause
           compilation errors.

           Example usage:

               barsrcs = ['bar.cpp'],
               barincs = ['bar.h'],
               barlocalincs = ['StdAfx.h']
               barresources = ['bar.rc','resource.h']
               barmisc = ['bar_readme.txt']

               dll = env.SharedLibrary(target = 'bar.dll',
                                       source = barsrcs)

               env.MSVSProject(target = 'Bar' + env['MSVSPROJECTSUFFIX'],
                               srcs = barsrcs,
                               incs = barincs,
                               localincs = barlocalincs,
                               resources = barresources,
                               misc = barmisc,
                               buildtarget = dll,
                               variant = 'Release')

           Starting with version 2.4 of SCons it's also possible to specify
           the optional argument DebugSettings, which creates files for
           debugging under Visual Studio:

           DebugSettings
               A dictionary of debug settings that get written to the
               .vcproj.user or the .vcxproj.user file, depending on the
               version installed. As it is done for cmdargs (see above), you
               can specify a DebugSettings dictionary per variant. If you give
               only one, it will be propagated to all variants.

           Currently, only Visual Studio v9.0 and Visual Studio version v11
           are implemented, for other versions no file is generated. To
           generate the user file, you just need to add a DebugSettings
           dictionary to the environment with the right parameters for your
           MSVS version. If the dictionary is empty, or does not contain any
           good value, no file will be generated.

           Following is a more contrived example, involving the setup of a
           project for variants and DebugSettings:

               # Assuming you store your defaults in a file
               vars = Variables('variables.py')
               msvcver = vars.args.get('vc', '9')

               # Check command args to force one Microsoft Visual Studio version
               if msvcver == '9' or msvcver == '11':
                 env = Environment(MSVC_VERSION=msvcver+'.0', MSVC_BATCH=False)
               else:
                 env = Environment()

               AddOption('--userfile', action='store_true', dest='userfile', default=False,
                         help="Create Visual Studio Project user file")

               #
               # 1. Configure your Debug Setting dictionary with options you want in the list
               # of allowed options, for instance if you want to create a user file to launch
               # a specific application for testing your dll with Microsoft Visual Studio 2008 (v9):
               #
               V9DebugSettings = {
                   'Command':'c:\\myapp\\using\\thisdll.exe',
                   'WorkingDirectory': 'c:\\myapp\\using\\',
                   'CommandArguments': '-p password',
               #     'Attach':'false',
               #     'DebuggerType':'3',
               #     'Remote':'1',
               #     'RemoteMachine': None,
               #     'RemoteCommand': None,
               #     'HttpUrl': None,
               #     'PDBPath': None,
               #     'SQLDebugging': None,
               #     'Environment': '',
               #     'EnvironmentMerge':'true',
               #     'DebuggerFlavor': None,
               #     'MPIRunCommand': None,
               #     'MPIRunArguments': None,
               #     'MPIRunWorkingDirectory': None,
               #     'ApplicationCommand': None,
               #     'ApplicationArguments': None,
               #     'ShimCommand': None,
               #     'MPIAcceptMode': None,
               #     'MPIAcceptFilter': None,
               }

               #
               # 2. Because there are a lot of different options depending on the Microsoft
               # Visual Studio version, if you use more than one version you have to
               # define a dictionary per version, for instance if you want to create a user
               # file to launch a specific application for testing your dll with Microsoft
               # Visual Studio 2012 (v11):
               #
               V10DebugSettings = {
                   'LocalDebuggerCommand': 'c:\\myapp\\using\\thisdll.exe',
                   'LocalDebuggerWorkingDirectory': 'c:\\myapp\\using\\',
                   'LocalDebuggerCommandArguments': '-p password',
               #     'LocalDebuggerEnvironment': None,
               #     'DebuggerFlavor': 'WindowsLocalDebugger',
               #     'LocalDebuggerAttach': None,
               #     'LocalDebuggerDebuggerType': None,
               #     'LocalDebuggerMergeEnvironment': None,
               #     'LocalDebuggerSQLDebugging': None,
               #     'RemoteDebuggerCommand': None,
               #     'RemoteDebuggerCommandArguments': None,
               #     'RemoteDebuggerWorkingDirectory': None,
               #     'RemoteDebuggerServerName': None,
               #     'RemoteDebuggerConnection': None,
               #     'RemoteDebuggerDebuggerType': None,
               #     'RemoteDebuggerAttach': None,
               #     'RemoteDebuggerSQLDebugging': None,
               #     'DeploymentDirectory': None,
               #     'AdditionalFiles': None,
               #     'RemoteDebuggerDeployDebugCppRuntime': None,
               #     'WebBrowserDebuggerHttpUrl': None,
               #     'WebBrowserDebuggerDebuggerType': None,
               #     'WebServiceDebuggerHttpUrl': None,
               #     'WebServiceDebuggerDebuggerType': None,
               #     'WebServiceDebuggerSQLDebugging': None,
               }

               #
               # 3. Select the dictionary you want depending on the version of visual Studio
               # Files you want to generate.
               #
               if not env.GetOption('userfile'):
                   dbgSettings = None
               elif env.get('MSVC_VERSION', None) == '9.0':
                   dbgSettings = V9DebugSettings
               elif env.get('MSVC_VERSION', None) == '11.0':
                   dbgSettings = V10DebugSettings
               else:
                   dbgSettings = None

               #
               # 4. Add the dictionary to the DebugSettings keyword.
               #
               barsrcs = ['bar.cpp', 'dllmain.cpp', 'stdafx.cpp']
               barincs = ['targetver.h']
               barlocalincs = ['StdAfx.h']
               barresources = ['bar.rc','resource.h']
               barmisc = ['ReadMe.txt']

               dll = env.SharedLibrary(target = 'bar.dll',
                                       source = barsrcs)

               env.MSVSProject(target = 'Bar' + env['MSVSPROJECTSUFFIX'],
                               srcs = barsrcs,
                               incs = barincs,
                               localincs = barlocalincs,
                               resources = barresources,
                               misc = barmisc,
                               buildtarget = [dll[0]] * 2,
                               variant = ('Debug|Win32', 'Release|Win32'),
                               cmdargs = 'vc=%s' %  msvcver,
                               DebugSettings = (dbgSettings, {}))

       MSVSSolution(), env.MSVSSolution()
           Builds a Microsoft Visual Studio solution file.

           This builds a Visual Studio solution file, based on the version of
           Visual Studio that is configured (either the latest installed
           version, or the version specified by $MSVS_VERSION in the
           construction environment). For Visual Studio 6, it will generate a
           .dsw file. For Visual Studio 7 (.NET), it will generate a .sln
           file.

           The following values must be specified:

           target
               The name of the target .dsw or .sln file. The correct suffix
               for the version of Visual Studio must be used, but the value
               $MSVSSOLUTIONSUFFIX will be defined to the correct value (see
               example below).

           variant
               The name of this particular variant, or a list of variant names
               (the latter is only supported for MSVS 7 solutions). These are
               typically things like "Debug" or "Release", but really can be
               anything you want. For MSVS 7 they may also specify target
               platform, like this "Debug|Xbox". Default platform is Win32.

           projects
               A list of project file names, or Project nodes returned by
               calls to the MSVSProject Builder, to be placed into the
               solution file. It should be noted that these file names are NOT
               added to the $SOURCES environment variable in form of files,
               but rather as strings. This is because they represent file
               names to be added to the solution file, not the source files
               used to build the solution file.

           Example Usage:

               env.MSVSSolution(target = 'Bar' + env['MSVSSOLUTIONSUFFIX'], projects = ['bar'
               + env['MSVSPROJECTSUFFIX']], variant = 'Release')

       Object(), env.Object()
           A synonym for the StaticObject builder method.

       Package(), env.Package()
           Builds a Binary Package of the given source files.

               env.Package(source = FindInstalledFiles())

           Builds software distribution packages. Packages consist of files to
           install and packaging information. The former may be specified with
           the source parameter and may be left out, in which case the
           FindInstalledFiles function will collect all files that have an
           Install or InstallAs Builder attached. If the target is not
           specified it will be deduced from additional information given to
           this Builder.

           The packaging information is specified with the help of
           construction variables documented below. This information is called
           a tag to stress that some of them can also be attached to files
           with the Tag function. The mandatory ones will complain if they
           were not specified. They vary depending on chosen target packager.

           The target packager may be selected with the "PACKAGETYPE" command
           line option or with the $PACKAGETYPE construction variable.
           Currently the following packagers available:

           * msi - Microsoft Installer * rpm - Redhat Package Manger * ipkg -
           Itsy Package Management System * tarbz2 - compressed tar * targz -
           compressed tar * zip - zip file * src_tarbz2 - compressed tar
           source * src_targz - compressed tar source * src_zip - zip file
           source

           An updated list is always available under the "package_type" option
           when running "scons --help" on a project that has packaging
           activated.

               env = Environment(tools=['default', 'packaging'])
               env.Install('/bin/', 'my_program')
               env.Package( NAME           = 'foo',
                            VERSION        = '1.2.3',
                            PACKAGEVERSION = 0,
                            PACKAGETYPE    = 'rpm',
                            LICENSE        = 'gpl',
                            SUMMARY        = 'balalalalal',
                            DESCRIPTION    = 'this should be really really long',
                            X_RPM_GROUP    = 'Application/fu',
                            SOURCE_URL     = 'http://foo.org/foo-1.2.3.tar.gz'
                       )

       PCH(), env.PCH()
           Builds a Microsoft Visual C++ precompiled header. Calling this
           builder method returns a list of two targets: the PCH as the first
           element, and the object file as the second element. Normally the
           object file is ignored. This builder method is only provided when
           Microsoft Visual C++ is being used as the compiler. The PCH builder
           method is generally used in conjunction with the PCH construction
           variable to force object files to use the precompiled header:

               env['PCH'] = env.PCH('StdAfx.cpp')[0]

       PDF(), env.PDF()
           Builds a .pdf file from a .dvi input file (or, by extension, a
           .tex, .ltx, or .latex input file). The suffix specified by the
           $PDFSUFFIX construction variable (.pdf by default) is added
           automatically to the target if it is not already present. Example:

               # builds from aaa.tex
               env.PDF(target = 'aaa.pdf', source = 'aaa.tex')
               # builds bbb.pdf from bbb.dvi
               env.PDF(target = 'bbb', source = 'bbb.dvi')

       POInit(), env.POInit()
           This builder belongs to msginit tool. The builder initializes
           missing PO file(s) if $POAUTOINIT is set. If $POAUTOINIT is not set
           (default), POInit prints instruction for user (that is supposed to
           be a translator), telling how the PO file should be initialized. In
           normal projects you should not use POInit and use POUpdate instead.
           POUpdate chooses intelligently between msgmerge(1) and msginit(1).
           POInit always uses msginit(1) and should be regarded as builder for
           special purposes or for temporary use (e.g. for quick, one time
           initialization of a bunch of PO files) or for tests.

           Target nodes defined through POInit are not built by default
           (they're Ignored from '.' node) but are added to special Alias
           ('po-create' by default). The alias name may be changed through the
           $POCREATE_ALIAS construction variable. All PO files defined through
           POInit may be easily initialized by scons po-create.


           Example 1. Initialize en.po and pl.po from messages.pot:

                 # ...
                 env.POInit(['en', 'pl']) # messages.pot --> [en.po, pl.po]


           Example 2. Initialize en.po and pl.po from foo.pot:

                 # ...
                 env.POInit(['en', 'pl'], ['foo']) # foo.pot --> [en.po, pl.po]


           Example 3. Initialize en.po and pl.po from foo.pot but using
           $POTDOMAIN construction variable:

                 # ...
                 env.POInit(['en', 'pl'], POTDOMAIN='foo') # foo.pot --> [en.po, pl.po]


           Example 4. Initialize PO files for languages defined in LINGUAS
           file. The files will be initialized from template messages.pot:

                 # ...
                 env.POInit(LINGUAS_FILE = 1) # needs 'LINGUAS' file


           Example 5. Initialize en.po and pl.pl PO files plus files for
           languages defined in LINGUAS file. The files will be initialized
           from template messages.pot:

                 # ...
                 env.POInit(['en', 'pl'], LINGUAS_FILE = 1)


           Example 6. You may preconfigure your environment first, and then
           initialize PO files:

                 # ...
                 env['POAUTOINIT'] = 1
                 env['LINGUAS_FILE'] = 1
                 env['POTDOMAIN'] = 'foo'
                 env.POInit()

           which has same efect as:

                 # ...
                 env.POInit(POAUTOINIT = 1, LINGUAS_FILE = 1, POTDOMAIN = 'foo')

       PostScript(), env.PostScript()
           Builds a .ps file from a .dvi input file (or, by extension, a .tex,
           .ltx, or .latex input file). The suffix specified by the $PSSUFFIX
           construction variable (.ps by default) is added automatically to
           the target if it is not already present. Example:

               # builds from aaa.tex
               env.PostScript(target = 'aaa.ps', source = 'aaa.tex')
               # builds bbb.ps from bbb.dvi
               env.PostScript(target = 'bbb', source = 'bbb.dvi')

       POTUpdate(), env.POTUpdate()
           The builder belongs to xgettext tool. The builder updates target
           POT file if exists or creates one if it doesn't. The node is not
           built by default (i.e. it is Ignored from '.'), but only on demand
           (i.e. when given POT file is required or when special alias is
           invoked). This builder adds its targe node (messages.pot, say) to a
           special alias (pot-update by default, see $POTUPDATE_ALIAS) so you
           can update/create them easily with scons pot-update. The file is
           not written until there is no real change in internationalized
           messages (or in comments that enter POT file).


               Note
               You may see xgettext(1) being invoked by the xgettext tool even
               if there is no real change in internationalized messages (so
               the POT file is not being updated). This happens every time a
               source file has changed. In such case we invoke xgettext(1) and
               compare its output with the content of POT file to decide
               whether the file should be updated or not.


           Example 1.  Let's create po/ directory and place following
           SConstruct script there:

                 # SConstruct in 'po/' subdir
                 env = Environment( tools = ['default', 'xgettext'] )
                 env.POTUpdate(['foo'], ['../a.cpp', '../b.cpp'])
                 env.POTUpdate(['bar'], ['../c.cpp', '../d.cpp'])

           Then invoke scons few times:

                 user@host:$ scons             # Does not create foo.pot nor bar.pot
                 user@host:$ scons foo.pot     # Updates or creates foo.pot
                 user@host:$ scons pot-update  # Updates or creates foo.pot and bar.pot
                 user@host:$ scons -c          # Does not clean foo.pot nor bar.pot.

           the results shall be as the comments above say.


           Example 2.  The POTUpdate builder may be used with no target
           specified, in which case default target messages.pot will be used.
           The default target may also be overridden by setting $POTDOMAIN
           construction variable or providing it as an override to POTUpdate
           builder:


                 # SConstruct script
                 env = Environment( tools = ['default', 'xgettext'] )
                 env['POTDOMAIN'] = "foo"
                 env.POTUpdate(source = ["a.cpp", "b.cpp"]) # Creates foo.pot ...
                 env.POTUpdate(POTDOMAIN = "bar", source = ["c.cpp", "d.cpp"]) # and bar.pot


           Example 3.  The sources may be specified within separate file, for
           example POTFILES.in:


                 # POTFILES.in in 'po/' subdirectory
                 ../a.cpp
                 ../b.cpp
                 # end of file

           The name of the file (POTFILES.in) containing the list of sources
           is provided via $XGETTEXTFROM:


                 # SConstruct file in 'po/' subdirectory
                 env = Environment( tools = ['default', 'xgettext'] )
                 env.POTUpdate(XGETTEXTFROM = 'POTFILES.in')


           Example 4.  You may use $XGETTEXTPATH to define source search path.
           Assume, for example, that you have files a.cpp, b.cpp,
           po/SConstruct, po/POTFILES.in. Then your POT-related files could
           look as below:

                 # POTFILES.in in 'po/' subdirectory
                 a.cpp
                 b.cpp
                 # end of file

                 # SConstruct file in 'po/' subdirectory
                 env = Environment( tools = ['default', 'xgettext'] )
                 env.POTUpdate(XGETTEXTFROM = 'POTFILES.in', XGETTEXTPATH='../')


           Example 5.  Multiple search directories may be defined within a
           list, i.e.  XGETTEXTPATH = ['dir1', 'dir2', ...]. The order in the
           list determines the search order of source files. The path to the
           first file found is used.

           Let's create 0/1/po/SConstruct script:

                 # SConstruct file in '0/1/po/' subdirectory
                 env = Environment( tools = ['default', 'xgettext'] )
                 env.POTUpdate(XGETTEXTFROM = 'POTFILES.in', XGETTEXTPATH=['../', '../../'])

           and 0/1/po/POTFILES.in:

                 # POTFILES.in in '0/1/po/' subdirectory
                 a.cpp
                 # end of file

           Write two *.cpp files, the first one is 0/a.cpp:

                 /* 0/a.cpp */
                 gettext("Hello from ../../a.cpp")

           and the second is 0/1/a.cpp:

                 /* 0/1/a.cpp */
                 gettext("Hello from ../a.cpp")

           then run scons. You'll obtain 0/1/po/messages.pot with the message
           "Hello from ../a.cpp". When you reverse order in $XGETTEXTFOM, i.e.
           when you write SConscript as

                 # SConstruct file in '0/1/po/' subdirectory
                 env = Environment( tools = ['default', 'xgettext'] )
                 env.POTUpdate(XGETTEXTFROM = 'POTFILES.in', XGETTEXTPATH=['../../', '../'])

           then the messages.pot will contain msgid "Hello from ../../a.cpp"
           line and not msgid "Hello from ../a.cpp".

       POUpdate(), env.POUpdate()
           The builder belongs to msgmerge tool. The builder updates PO files
           with msgmerge(1), or initializes missing PO files as described in
           documentation of msginit tool and POInit builder (see also
           $POAUTOINIT). Note, that POUpdate does not add its targets to
           po-create alias as POInit does.

           Target nodes defined through POUpdate are not built by default
           (they're Ignored from '.' node). Instead, they are added
           automatically to special Alias ('po-update' by default). The alias
           name may be changed through the $POUPDATE_ALIAS construction
           variable. You can easily update PO files in your project by scons
           po-update.


           Example 1.  Update en.po and pl.po from messages.pot template (see
           also $POTDOMAIN), assuming that the later one exists or there is
           rule to build it (see POTUpdate):

                 # ...
                 env.POUpdate(['en','pl']) # messages.pot --> [en.po, pl.po]


           Example 2.  Update en.po and pl.po from foo.pot template:

                 # ...
                 env.POUpdate(['en', 'pl'], ['foo']) # foo.pot -->  [en.po, pl.pl]


           Example 3.  Update en.po and pl.po from foo.pot (another version):

                 # ...
                 env.POUpdate(['en', 'pl'], POTDOMAIN='foo') # foo.pot -- > [en.po, pl.pl]


           Example 4.  Update files for languages defined in LINGUAS file. The
           files are updated from messages.pot template:

                 # ...
                 env.POUpdate(LINGUAS_FILE = 1) # needs 'LINGUAS' file


           Example 5.  Same as above, but update from foo.pot template:

                 # ...
                 env.POUpdate(LINGUAS_FILE = 1, source = ['foo'])


           Example 6.  Update en.po and pl.po plus files for languages defined
           in LINGUAS file. The files are updated from messages.pot template:

                 # produce 'en.po', 'pl.po' + files defined in 'LINGUAS':
                 env.POUpdate(['en', 'pl' ], LINGUAS_FILE = 1)


           Example 7.  Use $POAUTOINIT to automatically initialize PO file if
           it doesn't exist:

                 # ...
                 env.POUpdate(LINGUAS_FILE = 1, POAUTOINIT = 1)


           Example 8.  Update PO files for languages defined in LINGUAS file.
           The files are updated from foo.pot template. All necessary settings
           are pre-configured via environment.

                 # ...
                 env['POAUTOINIT'] = 1
                 env['LINGUAS_FILE'] = 1
                 env['POTDOMAIN'] = 'foo'
                 env.POUpdate()

       Program(), env.Program()
           Builds an executable given one or more object files or C, C++, D,
           or Fortran source files. If any C, C++, D or Fortran source files
           are specified, then they will be automatically compiled to object
           files using the Object builder method; see that builder method's
           description for a list of legal source file suffixes and how they
           are interpreted. The target executable file prefix (specified by
           the $PROGPREFIX construction variable; nothing by default) and
           suffix (specified by the $PROGSUFFIX construction variable; by
           default, .exe on Windows systems, nothing on POSIX systems) are
           automatically added to the target if not already present. Example:

               env.Program(target = 'foo', source = ['foo.o', 'bar.c', 'baz.f'])

       RES(), env.RES()
           Builds a Microsoft Visual C++ resource file. This builder method is
           only provided when Microsoft Visual C++ or MinGW is being used as
           the compiler. The .res (or .o for MinGW) suffix is added to the
           target name if no other suffix is given. The source file is scanned
           for implicit dependencies as though it were a C file. Example:

               env.RES('resource.rc')

       RMIC(), env.RMIC()
           Builds stub and skeleton class files for remote objects from Java
           .class files. The target is a directory relative to which the stub
           and skeleton class files will be written. The source can be the
           names of .class files, or the objects return from the Java builder
           method.

           If the construction variable $JAVACLASSDIR is set, either in the
           environment or in the call to the RMIC builder method itself, then
           the value of the variable will be stripped from the beginning of
           any .class file names.

               classes = env.Java(target = 'classdir', source = 'src')
               env.RMIC(target = 'outdir1', source = classes)

               env.RMIC(target = 'outdir2',
                        source = ['package/foo.class', 'package/bar.class'])

               env.RMIC(target = 'outdir3',
                        source = ['classes/foo.class', 'classes/bar.class'],
                        JAVACLASSDIR = 'classes')

       RPCGenClient(), env.RPCGenClient()
           Generates an RPC client stub (_clnt.c) file from a specified RPC
           (.x) source file. Because rpcgen only builds output files in the
           local directory, the command will be executed in the source file's
           directory by default.

               # Builds src/rpcif_clnt.c
               env.RPCGenClient('src/rpcif.x')

       RPCGenHeader(), env.RPCGenHeader()
           Generates an RPC header (.h) file from a specified RPC (.x) source
           file. Because rpcgen only builds output files in the local
           directory, the command will be executed in the source file's
           directory by default.

               # Builds src/rpcif.h
               env.RPCGenHeader('src/rpcif.x')

       RPCGenService(), env.RPCGenService()
           Generates an RPC server-skeleton (_svc.c) file from a specified RPC
           (.x) source file. Because rpcgen only builds output files in the
           local directory, the command will be executed in the source file's
           directory by default.

               # Builds src/rpcif_svc.c
               env.RPCGenClient('src/rpcif.x')

       RPCGenXDR(), env.RPCGenXDR()
           Generates an RPC XDR routine (_xdr.c) file from a specified RPC
           (.x) source file. Because rpcgen only builds output files in the
           local directory, the command will be executed in the source file's
           directory by default.

               # Builds src/rpcif_xdr.c
               env.RPCGenClient('src/rpcif.x')

       SharedLibrary(), env.SharedLibrary()
           Builds a shared library (.so on a POSIX system, .dll on Windows)
           given one or more object files or C, C++, D or Fortran source
           files. If any source files are given, then they will be
           automatically compiled to object files. The static library prefix
           and suffix (if any) are automatically added to the target. The
           target library file prefix (specified by the $SHLIBPREFIX
           construction variable; by default, lib on POSIX systems, nothing on
           Windows systems) and suffix (specified by the $SHLIBSUFFIX
           construction variable; by default, .dll on Windows systems, .so on
           POSIX systems) are automatically added to the target if not already
           present. Example:

               env.SharedLibrary(target = 'bar', source = ['bar.c', 'foo.o'])

           On Windows systems, the SharedLibrary builder method will always
           build an import (.lib) library in addition to the shared (.dll)
           library, adding a .lib library with the same basename if there is
           not already a .lib file explicitly listed in the targets.

           On Cygwin systems, the SharedLibrary builder method will always
           build an import (.dll.a) library in addition to the shared (.dll)
           library, adding a .dll.a library with the same basename if there is
           not already a .dll.a file explicitly listed in the targets.

           Any object files listed in the source must have been built for a
           shared library (that is, using the SharedObject builder method).
           scons will raise an error if there is any mismatch.

           On some platforms, there is a distinction between a shared library
           (loaded automatically by the system to resolve external references)
           and a loadable module (explicitly loaded by user action). For
           maximum portability, use the LoadableModule builder for the latter.

           When the $SHLIBVERSION construction variable is defined a versioned
           shared library is created. This modifies the $SHLINKFLAGS as
           required, adds the version number to the library name, and creates
           the symlinks that are needed.

               env.SharedLibrary(target = 'bar', source = ['bar.c', 'foo.o'], SHLIBVERSION='1.5.2')

           On a POSIX system, versions with a single token create exactly one
           symlink: libbar.so.6 would have symlinks libbar.so only. On a POSIX
           system, versions with two or more tokens create exactly two
           symlinks: libbar.so.2.3.1 would have symlinks libbar.so and
           libbar.so.2; on a Darwin (OSX) system the library would be
           libbar.2.3.1.dylib and the link would be libbar.dylib.

           On Windows systems, specifying register=1 will cause the .dll to be
           registered after it is built using REGSVR32. The command that is
           run ("regsvr32" by default) is determined by $REGSVR construction
           variable, and the flags passed are determined by $REGSVRFLAGS. By
           default, $REGSVRFLAGS includes the /s option, to prevent dialogs
           from popping up and requiring user attention when it is run. If you
           change $REGSVRFLAGS, be sure to include the /s option. For example,

               env.SharedLibrary(target = 'bar',
                                 source = ['bar.cxx', 'foo.obj'],
                                 register=1)

           will register bar.dll as a COM object when it is done linking it.

       SharedObject(), env.SharedObject()
           Builds an object file for inclusion in a shared library. Source
           files must have one of the same set of extensions specified above
           for the StaticObject builder method. On some platforms building a
           shared object requires additional compiler option (e.g.  -fPIC for
           gcc) in addition to those needed to build a normal (static) object,
           but on some platforms there is no difference between a shared
           object and a normal (static) one. When there is a difference, SCons
           will only allow shared objects to be linked into a shared library,
           and will use a different suffix for shared objects. On platforms
           where there is no difference, SCons will allow both normal (static)
           and shared objects to be linked into a shared library, and will use
           the same suffix for shared and normal (static) objects. The target
           object file prefix (specified by the $SHOBJPREFIX construction
           variable; by default, the same as $OBJPREFIX) and suffix (specified
           by the $SHOBJSUFFIX construction variable) are automatically added
           to the target if not already present. Examples:

               env.SharedObject(target = 'ddd', source = 'ddd.c')
               env.SharedObject(target = 'eee.o', source = 'eee.cpp')
               env.SharedObject(target = 'fff.obj', source = 'fff.for')

           Note that the source files will be scanned according to the suffix
           mappings in the SourceFileScanner object. See the section "Scanner
           Objects," below, for more information.

       StaticLibrary(), env.StaticLibrary()
           Builds a static library given one or more object files or C, C++, D
           or Fortran source files. If any source files are given, then they
           will be automatically compiled to object files. The static library
           prefix and suffix (if any) are automatically added to the target.
           The target library file prefix (specified by the $LIBPREFIX
           construction variable; by default, lib on POSIX systems, nothing on
           Windows systems) and suffix (specified by the $LIBSUFFIX
           construction variable; by default, .lib on Windows systems, .a on
           POSIX systems) are automatically added to the target if not already
           present. Example:

               env.StaticLibrary(target = 'bar', source = ['bar.c', 'foo.o'])

           Any object files listed in the source must have been built for a
           static library (that is, using the StaticObject builder method).
           scons will raise an error if there is any mismatch.

       StaticObject(), env.StaticObject()
           Builds a static object file from one or more C, C++, D, or Fortran
           source files. Source files must have one of the following
           extensions:

                 .asm    assembly language file
                 .ASM    assembly language file
                 .c      C file
                 .C      Windows:  C file
                         POSIX:  C++ file
                 .cc     C++ file
                 .cpp    C++ file
                 .cxx    C++ file
                 .cxx    C++ file
                 .c++    C++ file
                 .C++    C++ file
                 .d      D file
                 .f      Fortran file
                 .F      Windows:  Fortran file
                         POSIX:  Fortran file + C pre-processor
                 .for    Fortran file
                 .FOR    Fortran file
                 .fpp    Fortran file + C pre-processor
                 .FPP    Fortran file + C pre-processor
                 .m      Object C file
                 .mm     Object C++ file
                 .s      assembly language file
                 .S      Windows:  assembly language file
                         ARM: CodeSourcery Sourcery Lite
                 .sx     assembly language file + C pre-processor
                         POSIX:  assembly language file + C pre-processor
                 .spp    assembly language file + C pre-processor
                 .SPP    assembly language file + C pre-processor

           The target object file prefix (specified by the $OBJPREFIX
           construction variable; nothing by default) and suffix (specified by
           the $OBJSUFFIX construction variable; .obj on Windows systems, .o
           on POSIX systems) are automatically added to the target if not
           already present. Examples:

               env.StaticObject(target = 'aaa', source = 'aaa.c')
               env.StaticObject(target = 'bbb.o', source = 'bbb.c++')
               env.StaticObject(target = 'ccc.obj', source = 'ccc.f')

           Note that the source files will be scanned according to the suffix
           mappings in SourceFileScanner object. See the section "Scanner
           Objects," below, for more information.

       Substfile(), env.Substfile()
           The Substfile builder creates a single text file from another file
           or set of files by concatenating them with $LINESEPARATOR and
           replacing text using the $SUBST_DICT construction variable. Nested
           lists of source files are flattened. See also Textfile.

           If a single source file is present with an .in suffix, the suffix
           is stripped and the remainder is used as the default target name.

           The prefix and suffix specified by the $SUBSTFILEPREFIX and
           $SUBSTFILESUFFIX construction variables (the null string by default
           in both cases) are automatically added to the target if they are
           not already present.

           If a construction variable named $SUBST_DICT is present, it may be
           either a Python dictionary or a sequence of (key,value) tuples. If
           it is a dictionary it is converted into a list of tuples in an
           arbitrary order, so if one key is a prefix of another key or if one
           substitution could be further expanded by another subsitition, it
           is unpredictable whether the expansion will occur.

           Any occurrences of a key in the source are replaced by the
           corresponding value, which may be a Python callable function or a
           string. If the value is a callable, it is called with no arguments
           to get a string. Strings are subst-expanded and the result replaces
           the key.

               env = Environment(tools = ['default', 'textfile'])

               env['prefix'] = '/usr/bin'
               script_dict = {'@prefix@': '/bin', @exec_prefix@: '$prefix'}
               env.Substfile('script.in', SUBST_DICT = script_dict)

               conf_dict = {'%VERSION%': '1.2.3', '%BASE%': 'MyProg'}
               env.Substfile('config.h.in', conf_dict, SUBST_DICT = conf_dict)

               # UNPREDICTABLE - one key is a prefix of another
               bad_foo = {'$foo': '$foo', '$foobar': '$foobar'}
               env.Substfile('foo.in', SUBST_DICT = bad_foo)

               # PREDICTABLE - keys are applied longest first
               good_foo = [('$foobar', '$foobar'), ('$foo', '$foo')]
               env.Substfile('foo.in', SUBST_DICT = good_foo)

               # UNPREDICTABLE - one substitution could be futher expanded
               bad_bar = {'@bar@': '@soap@', '@soap@': 'lye'}
               env.Substfile('bar.in', SUBST_DICT = bad_bar)

               # PREDICTABLE - substitutions are expanded in order
               good_bar = (('@bar@', '@soap@'), ('@soap@', 'lye'))
               env.Substfile('bar.in', SUBST_DICT = good_bar)

               # the SUBST_DICT may be in common (and not an override)
               substutions = {}
               subst = Environment(tools = ['textfile'], SUBST_DICT = substitutions)
               substitutions['@foo@'] = 'foo'
               subst['SUBST_DICT']['@bar@'] = 'bar'
               subst.Substfile('pgm1.c', [Value('#include "@foo@.h"'),
                                          Value('#include "@bar@.h"'),
                                          "common.in",
                                          "pgm1.in"
                                         ])
               subst.Substfile('pgm2.c', [Value('#include "@foo@.h"'),
                                          Value('#include "@bar@.h"'),
                                          "common.in",
                                          "pgm2.in"
                                         ])


       Tar(), env.Tar()
           Builds a tar archive of the specified files and/or directories.
           Unlike most builder methods, the Tar builder method may be called
           multiple times for a given target; each additional call adds to the
           list of entries that will be built into the archive. Any source
           directories will be scanned for changes to any on-disk files,
           regardless of whether or not scons knows about them from other
           Builder or function calls.

               env.Tar('src.tar', 'src')

               # Create the stuff.tar file.
               env.Tar('stuff', ['subdir1', 'subdir2'])
               # Also add "another" to the stuff.tar file.
               env.Tar('stuff', 'another')

               # Set TARFLAGS to create a gzip-filtered archive.
               env = Environment(TARFLAGS = '-c -z')
               env.Tar('foo.tar.gz', 'foo')

               # Also set the suffix to .tgz.
               env = Environment(TARFLAGS = '-c -z',
                                 TARSUFFIX = '.tgz')
               env.Tar('foo')

       Textfile(), env.Textfile()
           The Textfile builder generates a single text file. The source
           strings constitute the lines; nested lists of sources are
           flattened.  $LINESEPARATOR is used to separate the strings.

           If present, the $SUBST_DICT construction variable is used to modify
           the strings before they are written; see the Substfile description
           for details.

           The prefix and suffix specified by the $TEXTFILEPREFIX and
           $TEXTFILESUFFIX construction variables (the null string and .txt by
           default, respectively) are automatically added to the target if
           they are not already present. Examples:

               # builds/writes foo.txt
               env.Textfile(target = 'foo.txt', source = ['Goethe', 42, 'Schiller'])

               # builds/writes bar.txt
               env.Textfile(target = 'bar',
                            source = ['lalala', 'tanteratei'],
                            LINESEPARATOR='|*')

               # nested lists are flattened automatically
               env.Textfile(target = 'blob',
                            source = ['lalala', ['Goethe', 42 'Schiller'], 'tanteratei'])

               # files may be used as input by wraping them in File()
               env.Textfile(target = 'concat',  # concatenate files with a marker between
                            source = [File('concat1'), File('concat2')],
                            LINESEPARATOR = '====================\n')

               Results are:
               foo.txt
                 ....8<----
                 Goethe
                 42
                 Schiller
                 ....8<---- (no linefeed at the end)

               bar.txt:
                 ....8<----
                 lalala|*tanteratei
                 ....8<---- (no linefeed at the end)

               blob.txt
                 ....8<----
                 lalala
                 Goethe
                 42
                 Schiller
                 tanteratei
                 ....8<---- (no linefeed at the end)

       Translate(), env.Translate()
           This pseudo-builder belongs to gettext toolset. The builder
           extracts internationalized messages from source files, updates POT
           template (if necessary) and then updates PO translations (if
           necessary). If $POAUTOINIT is set, missing PO files will be
           automatically created (i.e. without translator person
           intervention). The variables $LINGUAS_FILE and $POTDOMAIN are taken
           into acount too. All other construction variables used by
           POTUpdate, and POUpdate work here too.


           Example 1. The simplest way is to specify input files and output
           languages inline in a SCons script when invoking Translate

               # SConscript in 'po/' directory
               env = Environment( tools = ["default", "gettext"] )
               env['POAUTOINIT'] = 1
               env.Translate(['en','pl'], ['../a.cpp','../b.cpp'])


           Example 2. If you wish, you may also stick to conventional style
           known from autotools, i.e. using POTFILES.in and LINGUAS files

               # LINGUAS
               en pl
               #end

               # POTFILES.in
               a.cpp
               b.cpp
               # end

               # SConscript
               env = Environment( tools = ["default", "gettext"] )
               env['POAUTOINIT'] = 1
               env['XGETTEXTPATH'] = ['../']
               env.Translate(LINGUAS_FILE = 1, XGETTEXTFROM = 'POTFILES.in')

           The last approach is perhaps the recommended one. It allows easily
           split internationalization/localization onto separate SCons
           scripts, where a script in source tree is responsible for
           translations (from sources to PO files) and script(s) under variant
           directories are responsible for compilation of PO to MO files to
           and for installation of MO files. The "gluing factor" synchronizing
           these two scripts is then the content of LINGUAS file. Note, that
           the updated POT and PO files are usually going to be committed back
           to the repository, so they must be updated within the source
           directory (and not in variant directories). Additionaly, the file
           listing of po/ directory contains LINGUAS file, so the source tree
           looks familiar to translators, and they may work with the project
           in their usual way.


           Example 3. Let's prepare a development tree as below

                project/
                 + SConstruct
                 + build/
                 + src/
                     + po/
                         + SConscript
                         + SConscript.i18n
                         + POTFILES.in
                         + LINGUAS

           with build being variant directory. Write the top-level SConstruct
           script as follows

                 # SConstruct
                 env = Environment( tools = ["default", "gettext"] )
                 VariantDir('build', 'src', duplicate = 0)
                 env['POAUTOINIT'] = 1
                 SConscript('src/po/SConscript.i18n', exports = 'env')
                 SConscript('build/po/SConscript', exports = 'env')

           the src/po/SConscript.i18n as

                 # src/po/SConscript.i18n
                 Import('env')
                 env.Translate(LINGUAS_FILE=1, XGETTEXTFROM='POTFILES.in', XGETTEXTPATH=['../'])

           and the src/po/SConscript

                 # src/po/SConscript
                 Import('env')
                 env.MOFiles(LINGUAS_FILE = 1)

           Such setup produces POT and PO files under source tree in src/po/
           and binary MO files under variant tree in build/po/. This way the
           POT and PO files are separated from other output files, which must
           not be committed back to source repositories (e.g.  MO files).


               Note
               In above example, the PO files are not updated, nor created
               automatically when you issue scons '.' command. The files must
               be updated (created) by hand via scons po-update and then MO
               files can be compiled by running scons '.'.

       TypeLibrary(), env.TypeLibrary()
           Builds a Windows type library (.tlb) file from an input IDL file
           (.idl). In addition, it will build the associated interface stub
           and proxy source files, naming them according to the base name of
           the .idl file. For example,

               env.TypeLibrary(source="foo.idl")

           Will create foo.tlb, foo.h, foo_i.c, foo_p.c and foo_data.c files.

       Uic(), env.Uic()
           Builds a header file, an implementation file and a moc file from an
           ui file. and returns the corresponding nodes in the above order.
           This builder is only available after using the tool 'qt'. Note: you
           can specify .ui files directly as source files to the Program,
           Library and SharedLibrary builders without using this builder.
           Using this builder lets you override the standard naming
           conventions (be careful: prefixes are always prepended to names of
           built files; if you don't want prefixes, you may set them to ``).
           See the $QTDIR variable for more information. Example:

               env.Uic('foo.ui') # -> ['foo.h', 'uic_foo.cc', 'moc_foo.cc']
               env.Uic(target = Split('include/foo.h gen/uicfoo.cc gen/mocfoo.cc'),
                       source = 'foo.ui') # -> ['include/foo.h', 'gen/uicfoo.cc', 'gen/mocfoo.cc']

       Zip(), env.Zip()
           Builds a zip archive of the specified files and/or directories.
           Unlike most builder methods, the Zip builder method may be called
           multiple times for a given target; each additional call adds to the
           list of entries that will be built into the archive. Any source
           directories will be scanned for changes to any on-disk files,
           regardless of whether or not scons knows about them from other
           Builder or function calls.

               env.Zip('src.zip', 'src')

               # Create the stuff.zip file.
               env.Zip('stuff', ['subdir1', 'subdir2'])
               # Also add "another" to the stuff.tar file.
               env.Zip('stuff', 'another')

       All targets of builder methods automatically depend on their sources.
       An explicit dependency can be specified using the Depends method of a
       construction environment (see below).

       In addition, scons automatically scans source files for various
       programming languages, so the dependencies do not need to be specified
       explicitly. By default, SCons can C source files, C++ source files,
       Fortran source files with .F (POSIX systems only), .fpp, or .FPP file
       extensions, and assembly language files with .S (POSIX systems only),
       .spp, or .SPP files extensions for C preprocessor dependencies. SCons
       also has default support for scanning D source files, You can also
       write your own Scanners to add support for additional source file
       types. These can be added to the default Scanner object used by the
       Object(), StaticObject(), and SharedObject() Builders by adding them to
       the SourceFileScanner object. See the section "Scanner Objects" below,
       for more information about defining your own Scanner objects and using
       the SourceFileScanner object.

   Methods and Functions to Do Things
       In addition to Builder methods, scons provides a number of other
       construction environment methods and global functions to manipulate the
       build configuration.

       Usually, a construction environment method and global function with the
       same name both exist so that you don't have to remember whether to a
       specific bit of functionality must be called with or without a
       construction environment. In the following list, if you call something
       as a global function it looks like:

           Function(arguments)

       and if you call something through a construction environment it looks
       like:

           env.Function(arguments)

       If you can call the functionality in both ways, then both forms are
       listed.

       Global functions may be called from custom Python modules that you
       import into an SConscript file by adding the following to the Python
       module:

           from SCons.Script import *

       Except where otherwise noted, the same-named construction environment
       method and global function provide the exact same functionality. The
       only difference is that, where appropriate, calling the functionality
       through a construction environment will substitute construction
       variables into any supplied strings. For example:

           env = Environment(FOO = 'foo')
           Default('$FOO')
           env.Default('$FOO')

       In the above example, the first call to the global Default() function
       will actually add a target named $FOO to the list of default targets,
       while the second call to the env.Default() construction environment
       method will expand the value and add a target named foo to the list of
       default targets. For more on construction variable expansion, see the
       next section on construction variables.

       Construction environment methods and global functions supported by
       scons include:

       Action(action, [cmd/str/fun, [var, ...]] [option=value, ...]),
       env.Action(action, [cmd/str/fun, [var, ...]] [option=value, ...])
           Creates an Action object for the specified action. See the section
           "Action Objects," below, for a complete explanation of the
           arguments and behavior.

           Note that the env.Action() form of the invocation will expand
           construction variables in any argument strings, including the
           action argument, at the time it is called using the construction
           variables in the env construction environment through which
           env.Action() was called. The Action() form delays all variable
           expansion until the Action object is actually used.

       AddMethod(object, function, [name]), env.AddMethod(function, [name])
           When called with the AddMethod() form, adds the specified function
           to the specified object as the specified method name. When called
           with the env.AddMethod() form, adds the specified function to the
           construction environment env as the specified method name. In both
           cases, if name is omitted or None, the name of the specified
           function itself is used for the method name.

           Examples:

               # Note that the first argument to the function to
               # be attached as a method must be the object through
               # which the method will be called; the Python
               # convention is to call it 'self'.
               def my_method(self, arg):
                   print "my_method() got", arg

               # Use the global AddMethod() function to add a method
               # to the Environment class.  This
               AddMethod(Environment, my_method)
               env = Environment()
               env.my_method('arg')

               # Add the function as a method, using the function
               # name for the method call.
               env = Environment()
               env.AddMethod(my_method, 'other_method_name')
               env.other_method_name('another arg')

       AddOption(arguments)
           This function adds a new command-line option to be recognized. The
           specified arguments are the same as supported by the standard
           Python optparse.add_option() method (with a few additional
           capabilities noted below); see the documentation for optparse for a
           thorough discussion of its option-processing capabities.

           In addition to the arguments and values supported by the
           optparse.add_option() method, the SCons AddOption function allows
           you to set the nargs keyword value to '?' (a string with just the
           question mark) to indicate that the specified long option(s)
           take(s) an optional argument. When nargs = '?' is passed to the
           AddOption function, the const keyword argument may be used to
           supply the "default" value that should be used when the option is
           specified on the command line without an explicit argument.

           If no default= keyword argument is supplied when calling AddOption,
           the option will have a default value of None.

           Once a new command-line option has been added with AddOption, the
           option value may be accessed using GetOption or env.GetOption().
           The value may also be set, using SetOption or env.SetOption(), if
           conditions in a SConscript require overriding any default value.
           Note, however, that a value specified on the command line will
           always override a value set by any SConscript file.

           Any specified help= strings for the new option(s) will be displayed
           by the -H or -h options (the latter only if no other help text is
           specified in the SConscript files). The help text for the local
           options specified by AddOption will appear below the SCons options
           themselves, under a separate Local Options heading. The options
           will appear in the help text in the order in which the AddOption
           calls occur.

           Example:

               AddOption('--prefix',
                         dest='prefix',
                         nargs=1, type='string',
                         action='store',
                         metavar='DIR',
                         help='installation prefix')
               env = Environment(PREFIX = GetOption('prefix'))

       AddPostAction(target, action), env.AddPostAction(target, action)
           Arranges for the specified action to be performed after the
           specified target has been built. The specified action(s) may be an
           Action object, or anything that can be converted into an Action
           object (see below).

           When multiple targets are supplied, the action may be called
           multiple times, once after each action that generates one or more
           targets in the list.

       AddPreAction(target, action), env.AddPreAction(target, action)
           Arranges for the specified action to be performed before the
           specified target is built. The specified action(s) may be an Action
           object, or anything that can be converted into an Action object
           (see below).

           When multiple targets are specified, the action(s) may be called
           multiple times, once before each action that generates one or more
           targets in the list.

           Note that if any of the targets are built in multiple steps, the
           action will be invoked just before the "final" action that
           specifically generates the specified target(s). For example, when
           building an executable program from a specified source .c file via
           an intermediate object file:

               foo = Program('foo.c')
               AddPreAction(foo, 'pre_action')

           The specified pre_action would be executed before scons calls the
           link command that actually generates the executable program binary
           foo, not before compiling the foo.c file into an object file.

       Alias(alias, [targets, [action]]), env.Alias(alias, [targets,
       [action]])
           Creates one or more phony targets that expand to one or more other
           targets. An optional action (command) or list of actions can be
           specified that will be executed whenever the any of the alias
           targets are out-of-date. Returns the Node object representing the
           alias, which exists outside of any file system. This Node object,
           or the alias name, may be used as a dependency of any other target,
           including another alias.  Alias can be called multiple times for
           the same alias to add additional targets to the alias, or
           additional actions to the list for this alias.

           Examples:

               Alias('install')
               Alias('install', '/usr/bin')
               Alias(['install', 'install-lib'], '/usr/local/lib')

               env.Alias('install', ['/usr/local/bin', '/usr/local/lib'])
               env.Alias('install', ['/usr/local/man'])

               env.Alias('update', ['file1', 'file2'], "update_database $SOURCES")

       AllowSubstExceptions([exception, ...])
           Specifies the exceptions that will be allowed when expanding
           construction variables. By default, any construction variable
           expansions that generate a NameError or IndexError exception will
           expand to a '' (a null string) and not cause scons to fail. All
           exceptions not in the specified list will generate an error message
           and terminate processing.

           If AllowSubstExceptions is called multiple times, each call
           completely overwrites the previous list of allowed exceptions.

           Example:

               # Requires that all construction variable names exist.
               # (You may wish to do this if you want to enforce strictly
               # that all construction variables must be defined before use.)
               AllowSubstExceptions()

               # Also allow a string containing a zero-division expansion
               # like '${1 / 0}' to evalute to ''.
               AllowSubstExceptions(IndexError, NameError, ZeroDivisionError)

       AlwaysBuild(target, ...), env.AlwaysBuild(target, ...)
           Marks each given target so that it is always assumed to be out of
           date, and will always be rebuilt if needed. Note, however, that
           AlwaysBuild does not add its target(s) to the default target list,
           so the targets will only be built if they are specified on the
           command line, or are a dependent of a target specified on the
           command line--but they will always be built if so specified.
           Multiple targets can be passed in to a single call to AlwaysBuild.

       env.Append(key=val, [...])
           Appends the specified keyword arguments to the end of construction
           variables in the environment. If the Environment does not have the
           specified construction variable, it is simply added to the
           environment. If the values of the construction variable and the
           keyword argument are the same type, then the two values will be
           simply added together. Otherwise, the construction variable and the
           value of the keyword argument are both coerced to lists, and the
           lists are added together. (See also the Prepend method, below.)

           Example:

               env.Append(CCFLAGS = ' -g', FOO = ['foo.yyy'])

       env.AppendENVPath(name, newpath, [envname, sep, delete_existing])
           This appends new path elements to the given path in the specified
           external environment (ENV by default). This will only add any
           particular path once (leaving the last one it encounters and
           ignoring the rest, to preserve path order), and to help assure
           this, will normalize all paths (using os.path.normpath and
           os.path.normcase). This can also handle the case where the given
           old path variable is a list instead of a string, in which case a
           list will be returned instead of a string.

           If delete_existing is 0, then adding a path that already exists
           will not move it to the end; it will stay where it is in the list.

           Example:

               print 'before:',env['ENV']['INCLUDE']
               include_path = '/foo/bar:/foo'
               env.AppendENVPath('INCLUDE', include_path)
               print 'after:',env['ENV']['INCLUDE']

               yields:
               before: /foo:/biz
               after: /biz:/foo/bar:/foo

       env.AppendUnique(key=val, [...], delete_existing=0)
           Appends the specified keyword arguments to the end of construction
           variables in the environment. If the Environment does not have the
           specified construction variable, it is simply added to the
           environment. If the construction variable being appended to is a
           list, then any value(s) that already exist in the construction
           variable will not be added again to the list. However, if
           delete_existing is 1, existing matching values are removed first,
           so existing values in the arg list move to the end of the list.

           Example:

               env.AppendUnique(CCFLAGS = '-g', FOO = ['foo.yyy'])

       env.BitKeeper()
           A factory function that returns a Builder object to be used to
           fetch source files using BitKeeper. The returned Builder is
           intended to be passed to the SourceCode function.

           This function is deprecated. For details, see the entry for the
           SourceCode function.

           Example:

               env.SourceCode('.', env.BitKeeper())

       BuildDir(build_dir, src_dir, [duplicate]), env.BuildDir(build_dir,
       src_dir, [duplicate])
           Deprecated synonyms for VariantDir and env.VariantDir(). The
           build_dir argument becomes the variant_dir argument of VariantDir
           or env.VariantDir().

       Builder(action, [arguments]), env.Builder(action, [arguments])
           Creates a Builder object for the specified action. See the section
           "Builder Objects," below, for a complete explanation of the
           arguments and behavior.

           Note that the env.Builder() form of the invocation will expand
           construction variables in any arguments strings, including the
           action argument, at the time it is called using the construction
           variables in the env construction environment through which
           env.Builder() was called. The Builder form delays all variable
           expansion until after the Builder object is actually called.

       CacheDir(cache_dir), env.CacheDir(cache_dir)
           Specifies that scons will maintain a cache of derived files in
           cache_dir. The derived files in the cache will be shared among all
           the builds using the same CacheDir call. Specifying a cache_dir of
           None disables derived file caching.

           Calling env.CacheDir() will only affect targets built through the
           specified construction environment. Calling CacheDir sets a global
           default that will be used by all targets built through construction
           environments that do not have an env.CacheDir() specified.

           When a CacheDir() is being used and scons finds a derived file that
           needs to be rebuilt, it will first look in the cache to see if a
           derived file has already been built from identical input files and
           an identical build action (as incorporated into the MD5 build
           signature). If so, scons will retrieve the file from the cache. If
           the derived file is not present in the cache, scons will rebuild it
           and then place a copy of the built file in the cache (identified by
           its MD5 build signature), so that it may be retrieved by other
           builds that need to build the same derived file from identical
           inputs.

           Use of a specified CacheDir may be disabled for any invocation by
           using the --cache-disable option.

           If the --cache-force option is used, scons will place a copy of all
           derived files in the cache, even if they already existed and were
           not built by this invocation. This is useful to populate a cache
           the first time CacheDir is added to a build, or after using the
           --cache-disable option.

           When using CacheDir, scons will report, "Retrieved `file' from
           cache," unless the --cache-show option is being used. When the
           --cache-show option is used, scons will print the action that would
           have been used to build the file, without any indication that the
           file was actually retrieved from the cache. This is useful to
           generate build logs that are equivalent regardless of whether a
           given derived file has been built in-place or retrieved from the
           cache.

           The NoCache method can be used to disable caching of specific
           files. This can be useful if inputs and/or outputs of some tool are
           impossible to predict or prohibitively large.

       Clean(targets, files_or_dirs), env.Clean(targets, files_or_dirs)
           This specifies a list of files or directories which should be
           removed whenever the targets are specified with the -c command line
           option. The specified targets may be a list or an individual
           target. Multiple calls to Clean are legal, and create new targets
           or add files and directories to the clean list for the specified
           targets.

           Multiple files or directories should be specified either as
           separate arguments to the Clean method, or as a list.  Clean will
           also accept the return value of any of the construction environment
           Builder methods. Examples:

           The related NoClean function overrides calling Clean for the same
           target, and any targets passed to both functions will not be
           removed by the -c option.

           Examples:

               Clean('foo', ['bar', 'baz'])
               Clean('dist', env.Program('hello', 'hello.c'))
               Clean(['foo', 'bar'], 'something_else_to_clean')

           In this example, installing the project creates a subdirectory for
           the documentation. This statement causes the subdirectory to be
           removed if the project is deinstalled.

               Clean(docdir, os.path.join(docdir, projectname))

       env.Clone([key=val, ...])
           Returns a separate copy of a construction environment. If there are
           any keyword arguments specified, they are added to the returned
           copy, overwriting any existing values for the keywords.

           Example:

               env2 = env.Clone()
               env3 = env.Clone(CCFLAGS = '-g')

           Additionally, a list of tools and a toolpath may be specified, as
           in the Environment constructor:

               def MyTool(env): env['FOO'] = 'bar'
               env4 = env.Clone(tools = ['msvc', MyTool])

           The parse_flags keyword argument is also recognized:

               # create an environment for compiling programs that use wxWidgets
               wx_env = env.Clone(parse_flags = '!wx-config --cflags --cxxflags')

       Command(target, source, action, [key=val, ...]), env.Command(target,
       source, action, [key=val, ...])
           Executes a specific action (or list of actions) to build a target
           file or files. This is more convenient than defining a separate
           Builder object for a single special-case build.

           As a special case, the source_scanner keyword argument can be used
           to specify a Scanner object that will be used to scan the sources.
           (The global DirScanner object can be used if any of the sources
           will be directories that must be scanned on-disk for changes to
           files that aren't already specified in other Builder of function
           calls.)

           Any other keyword arguments specified override any same-named
           existing construction variables.

           An action can be an external command, specified as a string, or a
           callable Python object; see "Action Objects," below, for more
           complete information. Also note that a string specifying an
           external command may be preceded by an @ (at-sign) to suppress
           printing the command in question, or by a - (hyphen) to ignore the
           exit status of the external command.

           Examples:

               env.Command('foo.out', 'foo.in',
                           "$FOO_BUILD < $SOURCES > $TARGET")

               env.Command('bar.out', 'bar.in',
                           ["rm -f $TARGET",
                            "$BAR_BUILD < $SOURCES > $TARGET"],
                           ENV = {'PATH' : '/usr/local/bin/'})

               def rename(env, target, source):
                   import os
                   os.rename('.tmp', str(target[0]))

               env.Command('baz.out', 'baz.in',
                           ["$BAZ_BUILD < $SOURCES > .tmp",
                         rename ])

           Note that the Command function will usually assume, by default,
           that the specified targets and/or sources are Files, if no other
           part of the configuration identifies what type of entry it is. If
           necessary, you can explicitly specify that targets or source nodes
           should be treated as directoriese by using the Dir or env.Dir()
           functions.

           Examples:

               env.Command('ddd.list', Dir('ddd'), 'ls -l $SOURCE > $TARGET')

               env['DISTDIR'] = 'destination/directory'
               env.Command(env.Dir('$DISTDIR')), None, make_distdir)

           (Also note that SCons will usually automatically create any
           directory necessary to hold a target file, so you normally don't
           need to create directories by hand.)

       Configure(env, [custom_tests, conf_dir, log_file, config_h]),
       env.Configure([custom_tests, conf_dir, log_file, config_h])
           Creates a Configure object for integrated functionality similar to
           GNU autoconf. See the section "Configure Contexts," below, for a
           complete explanation of the arguments and behavior.

       env.Copy([key=val, ...])
           A now-deprecated synonym for env.Clone().

       env.CVS(repository, module)
           A factory function that returns a Builder object to be used to
           fetch source files from the specified CVS repository. The returned
           Builder is intended to be passed to the SourceCode function.

           This function is deprecated. For details, see the entry for the
           SourceCode function.

           The optional specified module will be added to the beginning of all
           repository path names; this can be used, in essence, to strip
           initial directory names from the repository path names, so that you
           only have to replicate part of the repository directory hierarchy
           in your local build directory.

           Examples:

               # Will fetch foo/bar/src.c
               # from /usr/local/CVSROOT/foo/bar/src.c.
               env.SourceCode('.', env.CVS('/usr/local/CVSROOT'))

               # Will fetch bar/src.c
               # from /usr/local/CVSROOT/foo/bar/src.c.
               env.SourceCode('.', env.CVS('/usr/local/CVSROOT', 'foo'))

               # Will fetch src.c
               # from /usr/local/CVSROOT/foo/bar/src.c.
               env.SourceCode('.', env.CVS('/usr/local/CVSROOT', 'foo/bar'))

       Decider(function), env.Decider(function)
           Specifies that all up-to-date decisions for targets built through
           this construction environment will be handled by the specified
           function. The function can be one of the following strings that
           specify the type of decision function to be performed:

           timestamp-newer
               Specifies that a target shall be considered out of date and
               rebuilt if the dependency's timestamp is newer than the target
               file's timestamp. This is the behavior of the classic Make
               utility, and make can be used a synonym for timestamp-newer.

           timestamp-match
               Specifies that a target shall be considered out of date and
               rebuilt if the dependency's timestamp is different than the
               timestamp recorded the last time the target was built. This
               provides behavior very similar to the classic Make utility (in
               particular, files are not opened up so that their contents can
               be checksummed) except that the target will also be rebuilt if
               a dependency file has been restored to a version with an
               earlier timestamp, such as can happen when restoring files from
               backup archives.

           MD5
               Specifies that a target shall be considered out of date and
               rebuilt if the dependency's content has changed sine the last
               time the target was built, as determined be performing an MD5
               checksum on the dependency's contents and comparing it to the
               checksum recorded the last time the target was built.  content
               can be used as a synonym for MD5.

           MD5-timestamp
               Specifies that a target shall be considered out of date and
               rebuilt if the dependency's content has changed sine the last
               time the target was built, except that dependencies with a
               timestamp that matches the last time the target was rebuilt
               will be assumed to be up-to-date and not rebuilt. This provides
               behavior very similar to the MD5 behavior of always
               checksumming file contents, with an optimization of not
               checking the contents of files whose timestamps haven't
               changed. The drawback is that SCons will not detect if a file's
               content has changed but its timestamp is the same, as might
               happen in an automated script that runs a build, updates a
               file, and runs the build again, all within a single second.

           Examples:

               # Use exact timestamp matches by default.
               Decider('timestamp-match')

               # Use MD5 content signatures for any targets built
               # with the attached construction environment.
               env.Decider('content')

           In addition to the above already-available functions, the function
           argument may be an actual Python function that takes the following
           three arguments:

           dependency
               The Node (file) which should cause the target to be rebuilt if
               it has "changed" since the last tme target was built.

           target
               The Node (file) being built. In the normal case, this is what
               should get rebuilt if the dependency has "changed."

           prev_ni
               Stored information about the state of the dependency the last
               time the target was built. This can be consulted to match
               various file characteristics such as the timestamp, size, or
               content signature.

           The function should return a True (non-zero) value if the
           dependency has "changed" since the last time the target was built
           (indicating that the target should be rebuilt), and False (zero)
           otherwise (indicating that the target should not be rebuilt). Note
           that the decision can be made using whatever criteria are
           appopriate. Ignoring some or all of the function arguments is
           perfectly normal.

           Example:

               def my_decider(dependency, target, prev_ni):
                   return not os.path.exists(str(target))

               env.Decider(my_decider)

       Default(targets), env.Default(targets)
           This specifies a list of default targets, which will be built by
           scons if no explicit targets are given on the command line.
           Multiple calls to Default are legal, and add to the list of default
           targets.

           Multiple targets should be specified as separate arguments to the
           Default method, or as a list.  Default will also accept the Node
           returned by any of a construction environment's builder methods.

           Examples:

               Default('foo', 'bar', 'baz')
               env.Default(['a', 'b', 'c'])
               hello = env.Program('hello', 'hello.c')
               env.Default(hello)

           An argument to Default of None will clear all default targets.
           Later calls to Default will add to the (now empty) default-target
           list like normal.

           The current list of targets added using the Default function or
           method is available in the DEFAULT_TARGETS list; see below.

       DefaultEnvironment([args])
           Creates and returns a default construction environment object. This
           construction environment is used internally by SCons in order to
           execute many of the global functions in this list, and to fetch
           source files transparently from source code management systems.

       Depends(target, dependency), env.Depends(target, dependency)
           Specifies an explicit dependency; the target will be rebuilt
           whenever the dependency has changed. Both the specified target and
           dependency can be a string (usually the path name of a file or
           directory) or Node objects, or a list of strings or Node objects
           (such as returned by a Builder call). This should only be necessary
           for cases where the dependency is not caught by a Scanner for the
           file.

           Example:

               env.Depends('foo', 'other-input-file-for-foo')

               mylib = env.Library('mylib.c')
               installed_lib = env.Install('lib', mylib)
               bar = env.Program('bar.c')

               # Arrange for the library to be copied into the installation
               # directory before trying to build the "bar" program.
               # (Note that this is for example only.  A "real" library
               # dependency would normally be configured through the $LIBS
               # and $LIBPATH variables, not using an env.Depends() call.)

               env.Depends(bar, installed_lib)

       env.Dictionary([vars])
           Returns a dictionary object containing copies of all of the
           construction variables in the environment. If there are any
           variable names specified, only the specified construction variables
           are returned in the dictionary.

           Example:

               dict = env.Dictionary()
               cc_dict = env.Dictionary('CC', 'CCFLAGS', 'CCCOM')

       Dir(name, [directory]), env.Dir(name, [directory])
           This returns a Directory Node, an object that represents the
           specified directory name.  name can be a relative or absolute path.
           directory is an optional directory that will be used as the parent
           directory. If no directory is specified, the current script's
           directory is used as the parent.

           If name is a list, SCons returns a list of Dir nodes. Construction
           variables are expanded in name.

           Directory Nodes can be used anywhere you would supply a string as a
           directory name to a Builder method or function. Directory Nodes
           have attributes and methods that are useful in many situations; see
           "File and Directory Nodes," below.

       env.Dump([key])
           Returns a pretty printable representation of the environment.  key,
           if not None, should be a string containing the name of the variable
           of interest.

           This SConstruct:

               env=Environment()
               print env.Dump('CCCOM')

           will print:

               '$CC -c -o $TARGET $CCFLAGS $CPPFLAGS $_CPPDEFFLAGS $_CPPINCFLAGS $SOURCES'

           While this SConstruct:

               env=Environment()
               print env.Dump()

           will print:

               { 'AR': 'ar',
                 'ARCOM': '$AR $ARFLAGS $TARGET $SOURCES\n$RANLIB $RANLIBFLAGS $TARGET',
                 'ARFLAGS': ['r'],
                 'AS': 'as',
                 'ASCOM': '$AS $ASFLAGS -o $TARGET $SOURCES',
                 'ASFLAGS': [],
                 ...

       EnsurePythonVersion(major, minor), env.EnsurePythonVersion(major,
       minor)
           Ensure that the Python version is at least major.minor. This
           function will print out an error message and exit SCons with a
           non-zero exit code if the actual Python version is not late enough.

           Example:

               EnsurePythonVersion(2,2)

       EnsureSConsVersion(major, minor, [revision]),
       env.EnsureSConsVersion(major, minor, [revision])
           Ensure that the SCons version is at least major.minor, or
           major.minor.revision. if revision is specified. This function will
           print out an error message and exit SCons with a non-zero exit code
           if the actual SCons version is not late enough.

           Examples:

               EnsureSConsVersion(0,14)

               EnsureSConsVersion(0,96,90)

       Environment([key=value, ...]), env.Environment([key=value, ...])
           Return a new construction environment initialized with the
           specified key=value pairs.

       Execute(action, [strfunction, varlist]), env.Execute(action,
       [strfunction, varlist])
           Executes an Action object. The specified action may be an Action
           object (see the section "Action Objects," below, for a complete
           explanation of the arguments and behavior), or it may be a
           command-line string, list of commands, or executable Python
           function, each of which will be converted into an Action object and
           then executed. The exit value of the command or return value of the
           Python function will be returned.

           Note that scons will print an error message if the executed action
           fails--that is, exits with or returns a non-zero value.  scons will
           not, however, automatically terminate the build if the specified
           action fails. If you want the build to stop in response to a failed
           Execute call, you must explicitly check for a non-zero return
           value:

               Execute(Copy('file.out', 'file.in'))

               if Execute("mkdir sub/dir/ectory"):
                   # The mkdir failed, don't try to build.
                   Exit(1)

       Exit([value]), env.Exit([value])
           This tells scons to exit immediately with the specified value. A
           default exit value of 0 (zero) is used if no value is specified.

       Export(vars), env.Export(vars)
           This tells scons to export a list of variables from the current
           SConscript file to all other SConscript files. The exported
           variables are kept in a global collection, so subsequent calls to
           Export will over-write previous exports that have the same name.
           Multiple variable names can be passed to Export as separate
           arguments or as a list. Keyword arguments can be used to provide
           names and their values. A dictionary can be used to map variables
           to a different name when exported. Both local variables and global
           variables can be exported.

           Examples:

               env = Environment()
               # Make env available for all SConscript files to Import().
               Export("env")

               package = 'my_name'
               # Make env and package available for all SConscript files:.
               Export("env", "package")

               # Make env and package available for all SConscript files:
               Export(["env", "package"])

               # Make env available using the name debug:
               Export(debug = env)

               # Make env available using the name debug:
               Export({"debug":env})

           Note that the SConscript function supports an exports argument that
           makes it easier to to export a variable or set of variables to a
           single SConscript file. See the description of the SConscript
           function, below.

       File(name, [directory]), env.File(name, [directory])
           This returns a File Node, an object that represents the specified
           file name.  name can be a relative or absolute path.  directory is
           an optional directory that will be used as the parent directory.

           If name is a list, SCons returns a list of File nodes. Construction
           variables are expanded in name.

           File Nodes can be used anywhere you would supply a string as a file
           name to a Builder method or function. File Nodes have attributes
           and methods that are useful in many situations; see "File and
           Directory Nodes," below.

       FindFile(file, dirs), env.FindFile(file, dirs)
           Search for file in the path specified by dirs.  dirs may be a list
           of directory names or a single directory name. In addition to
           searching for files that exist in the filesystem, this function
           also searches for derived files that have not yet been built.

           Example:

               foo = env.FindFile('foo', ['dir1', 'dir2'])

       FindInstalledFiles(), env.FindInstalledFiles()
           Returns the list of targets set up by the Install or InstallAs
           builders.

           This function serves as a convenient method to select the contents
           of a binary package.

           Example:

               Install( '/bin', [ 'executable_a', 'executable_b' ] )

               # will return the file node list
               # [ '/bin/executable_a', '/bin/executable_b' ]
               FindInstalledFiles()

               Install( '/lib', [ 'some_library' ] )

               # will return the file node list
               # [ '/bin/executable_a', '/bin/executable_b', '/lib/some_library' ]
               FindInstalledFiles()

       FindPathDirs(variable)
           Returns a function (actually a callable Python object) intended to
           be used as the path_function of a Scanner object. The returned
           object will look up the specified variable in a construction
           environment and treat the construction variable's value as a list
           of directory paths that should be searched (like $CPPPATH,
           $LIBPATH, etc.).

           Note that use of FindPathDirs is generally preferable to writing
           your own path_function for the following reasons: 1) The returned
           list will contain all appropriate directories found in source trees
           (when VariantDir is used) or in code repositories (when Repository
           or the -Y option are used). 2) scons will identify expansions of
           variable that evaluate to the same list of directories as, in fact,
           the same list, and avoid re-scanning the directories for files,
           when possible.

           Example:

               def my_scan(node, env, path, arg):
                   # Code to scan file contents goes here...
                   return include_files

               scanner = Scanner(name = 'myscanner',
                                 function = my_scan,
                                 path_function = FindPathDirs('MYPATH'))

       FindSourceFiles(node='"."'), env.FindSourceFiles(node='"."')
           Returns the list of nodes which serve as the source of the built
           files. It does so by inspecting the dependency tree starting at the
           optional argument node which defaults to the '"."'-node. It will
           then return all leaves of node. These are all children which have
           no further children.

           This function is a convenient method to select the contents of a
           Source Package.

           Example:

               Program( 'src/main_a.c' )
               Program( 'src/main_b.c' )
               Program( 'main_c.c' )

               # returns ['main_c.c', 'src/main_a.c', 'SConstruct', 'src/main_b.c']
               FindSourceFiles()

               # returns ['src/main_b.c', 'src/main_a.c' ]
               FindSourceFiles( 'src' )

           As you can see build support files (SConstruct in the above
           example) will also be returned by this function.

       Flatten(sequence), env.Flatten(sequence)
           Takes a sequence (that is, a Python list or tuple) that may contain
           nested sequences and returns a flattened list containing all of the
           individual elements in any sequence. This can be helpful for
           collecting the lists returned by calls to Builders; other Builders
           will automatically flatten lists specified as input, but direct
           Python manipulation of these lists does not.

           Examples:

               foo = Object('foo.c')
               bar = Object('bar.c')

               # Because `foo' and `bar' are lists returned by the Object() Builder,
               # `objects' will be a list containing nested lists:
               objects = ['f1.o', foo, 'f2.o', bar, 'f3.o']

               # Passing such a list to another Builder is all right because
               # the Builder will flatten the list automatically:
               Program(source = objects)

               # If you need to manipulate the list directly using Python, you need to
               # call Flatten() yourself, or otherwise handle nested lists:
               for object in Flatten(objects):
                   print str(object)

       GetBuildFailures()
           Returns a list of exceptions for the actions that failed while
           attempting to build targets. Each element in the returned list is a
           BuildError object with the following attributes that record various
           aspects of the build failure:


           .node The node that was being built when the build failure
           occurred.


           .status The numeric exit status returned by the command or Python
           function that failed when trying to build the specified Node.


           .errstr The SCons error string describing the build failure. (This
           is often a generic message like "Error 2" to indicate that an
           executed command exited with a status of 2.)


           .filename The name of the file or directory that actually caused
           the failure. This may be different from the .node attribute. For
           example, if an attempt to build a target named sub/dir/target fails
           because the sub/dir directory could not be created, then the .node
           attribute will be sub/dir/target but the .filename attribute will
           be sub/dir.


           .executor The SCons Executor object for the target Node being
           built. This can be used to retrieve the construction environment
           used for the failed action.


           .action The actual SCons Action object that failed. This will be
           one specific action out of the possible list of actions that would
           have been executed to build the target.


           .command The actual expanded command that was executed and failed,
           after expansion of $TARGET, $SOURCE, and other construction
           variables.

           Note that the GetBuildFailures function will always return an empty
           list until any build failure has occurred, which means that
           GetBuildFailures will always return an empty list while the
           SConscript files are being read. Its primary intended use is for
           functions that will be executed before SCons exits by passing them
           to the standard Python atexit.register() function. Example:

               import atexit

               def print_build_failures():
                   from SCons.Script import GetBuildFailures
                   for bf in GetBuildFailures():
                       print "%s failed: %s" % (bf.node, bf.errstr)

               atexit.register(print_build_failures)

       GetBuildPath(file, [...]), env.GetBuildPath(file, [...])
           Returns the scons path name (or names) for the specified file (or
           files). The specified file or files may be scons Nodes or strings
           representing path names.

       GetLaunchDir(), env.GetLaunchDir()
           Returns the absolute path name of the directory from which scons
           was initially invoked. This can be useful when using the -u, -U or
           -D options, which internally change to the directory in which the
           SConstruct file is found.

       GetOption(name), env.GetOption(name)
           This function provides a way to query the value of SCons options
           set on scons command line (or set using the SetOption function).
           The options supported are:

           cache_debug
               which corresponds to --cache-debug;

           cache_disable
               which corresponds to --cache-disable;

           cache_force
               which corresponds to --cache-force;

           cache_show
               which corresponds to --cache-show;

           clean
               which corresponds to -c, --clean and --remove;

           config
               which corresponds to --config;

           directory
               which corresponds to -C and --directory;

           diskcheck
               which corresponds to --diskcheck

           duplicate
               which corresponds to --duplicate;

           file
               which corresponds to -f, --file, --makefile and --sconstruct;

           help
               which corresponds to -h and --help;

           ignore_errors
               which corresponds to --ignore-errors;

           implicit_cache
               which corresponds to --implicit-cache;

           implicit_deps_changed
               which corresponds to --implicit-deps-changed;

           implicit_deps_unchanged
               which corresponds to --implicit-deps-unchanged;

           interactive
               which corresponds to --interact and --interactive;

           keep_going
               which corresponds to -k and --keep-going;

           max_drift
               which corresponds to --max-drift;

           no_exec
               which corresponds to -n, --no-exec, --just-print, --dry-run and
               --recon;

           no_site_dir
               which corresponds to --no-site-dir;

           num_jobs
               which corresponds to -j and --jobs;

           profile_file
               which corresponds to --profile;

           question
               which corresponds to -q and --question;

           random
               which corresponds to --random;

           repository
               which corresponds to -Y, --repository and --srcdir;

           silent
               which corresponds to -s, --silent and --quiet;

           site_dir
               which corresponds to --site-dir;

           stack_size
               which corresponds to --stack-size;

           taskmastertrace_file
               which corresponds to --taskmastertrace; and

           warn
               which corresponds to --warn and --warning.

           See the documentation for the corresponding command line object for
           information about each specific option.

       Glob(pattern, [ondisk, source, strings, exclude]), env.Glob(pattern,
       [ondisk, source, strings, exclude])
           Returns Nodes (or strings) that match the specified pattern,
           relative to the directory of the current SConscript file. The
           env.Glob() form performs string substition on pattern and returns
           whatever matches the resulting expanded pattern.

           The specified pattern uses Unix shell style metacharacters for
           matching:

                 *       matches everything
                 ?       matches any single character
                 [seq]   matches any character in seq
                 [!seq]  matches any char not in seq

           If the first character of a filename is a dot, it must be matched
           explicitly. Character matches do not span directory separators.

           The Glob knows about repositories (see the Repository function) and
           source directories (see the VariantDir function) and returns a Node
           (or string, if so configured) in the local (SConscript) directory
           if matching Node is found anywhere in a corresponding repository or
           source directory.

           The ondisk argument may be set to False (or any other non-true
           value) to disable the search for matches on disk, thereby only
           returning matches among already-configured File or Dir Nodes. The
           default behavior is to return corresponding Nodes for any on-disk
           matches found.

           The source argument may be set to True (or any equivalent value) to
           specify that, when the local directory is a VariantDir, the
           returned Nodes should be from the corresponding source directory,
           not the local directory.

           The strings argument may be set to True (or any equivalent value)
           to have the Glob function return strings, not Nodes, that represent
           the matched files or directories. The returned strings will be
           relative to the local (SConscript) directory. (Note that This may
           make it easier to perform arbitrary manipulation of file names, but
           if the returned strings are passed to a different SConscript file,
           any Node translation will be relative to the other SConscript
           directory, not the original SConscript directory.)

           The exclude argument may be set to a pattern or a list of patterns
           (following the same Unix shell semantics) which must be filtered
           out of returned elements. Elements matching a least one pattern of
           this list will be excluded.

           Examples:

               Program('foo', Glob('*.c'))
               Zip('/tmp/everything', Glob('.??*') + Glob('*'))
               sources = Glob('*.cpp', exclude=['os_*_specific_*.cpp']) + Glob('os_%s_specific_*.cpp'%currentOS)

       Help(text, append=False), env.Help(text, append=False)
           This specifies help text to be printed if the -h argument is given
           to scons. If Help is called multiple times, the text is appended
           together in the order that Help is called. With append set to
           False, any Help text generated with AddOption is clobbered. If
           append is True, the AddOption help is prepended to the help string,
           thus preserving the -h message.

       Ignore(target, dependency), env.Ignore(target, dependency)
           The specified dependency file(s) will be ignored when deciding if
           the target file(s) need to be rebuilt.

           You can also use Ignore to remove a target from the default build.
           In order to do this you must specify the directory the target will
           be built in as the target, and the file you want to skip building
           as the dependency.

           Note that this will only remove the dependencies listed from the
           files built by default. It will still be built if that dependency
           is needed by another object being built. See the third and forth
           examples below.

           Examples:

               env.Ignore('foo', 'foo.c')
               env.Ignore('bar', ['bar1.h', 'bar2.h'])
               env.Ignore('.','foobar.obj')
               env.Ignore('bar','bar/foobar.obj')

       Import(vars), env.Import(vars)
           This tells scons to import a list of variables into the current
           SConscript file. This will import variables that were exported with
           Export or in the exports argument to SConscript. Variables exported
           by SConscript have precedence. Multiple variable names can be
           passed to Import as separate arguments or as a list. The variable
           "*" can be used to import all variables.

           Examples:

               Import("env")
               Import("env", "variable")
               Import(["env", "variable"])
               Import("*")

       Literal(string), env.Literal(string)
           The specified string will be preserved as-is and not have
           construction variables expanded.

       Local(targets), env.Local(targets)
           The specified targets will have copies made in the local tree, even
           if an already up-to-date copy exists in a repository. Returns a
           list of the target Node or Nodes.

       env.MergeFlags(arg, [unique])
           Merges the specified arg values to the construction environment's
           construction variables. If the arg argument is not a dictionary, it
           is converted to one by calling env.ParseFlags on the argument
           before the values are merged. Note that arg must be a single value,
           so multiple strings must be passed in as a list, not as separate
           arguments to env.MergeFlags.

           By default, duplicate values are eliminated; you can, however,
           specify unique=0 to allow duplicate values to be added. When
           eliminating duplicate values, any construction variables that end
           with the string PATH keep the left-most unique value. All other
           construction variables keep the right-most unique value.

           Examples:

               # Add an optimization flag to $CCFLAGS.
               env.MergeFlags('-O3')

               # Combine the flags returned from running pkg-config with an optimization
               # flag and merge the result into the construction variables.
               env.MergeFlags(['!pkg-config gtk+-2.0 --cflags', '-O3'])

               # Combine an optimization flag with the flags returned from running pkg-config
               # twice and merge the result into the construction variables.
               env.MergeFlags(['-O3',
                              '!pkg-config gtk+-2.0 --cflags --libs',
                              '!pkg-config libpng12 --cflags --libs'])

       NoCache(target, ...), env.NoCache(target, ...)
           Specifies a list of files which should not be cached whenever the
           CacheDir method has been activated. The specified targets may be a
           list or an individual target.

           Multiple files should be specified either as separate arguments to
           the NoCache method, or as a list.  NoCache will also accept the
           return value of any of the construction environment Builder
           methods.

           Calling NoCache on directories and other non-File Node types has no
           effect because only File Nodes are cached.

           Examples:

               NoCache('foo.elf')
               NoCache(env.Program('hello', 'hello.c'))

       NoClean(target, ...), env.NoClean(target, ...)
           Specifies a list of files or directories which should not be
           removed whenever the targets (or their dependencies) are specified
           with the -c command line option. The specified targets may be a
           list or an individual target. Multiple calls to NoClean are legal,
           and prevent each specified target from being removed by calls to
           the -c option.

           Multiple files or directories should be specified either as
           separate arguments to the NoClean method, or as a list.  NoClean
           will also accept the return value of any of the construction
           environment Builder methods.

           Calling NoClean for a target overrides calling Clean for the same
           target, and any targets passed to both functions will not be
           removed by the -c option.

           Examples:

               NoClean('foo.elf')
               NoClean(env.Program('hello', 'hello.c'))

       env.ParseConfig(command, [function, unique])
           Calls the specified function to modify the environment as specified
           by the output of command. The default function is env.MergeFlags,
           which expects the output of a typical *-config command (for
           example, gtk-config) and adds the options to the appropriate
           construction variables. By default, duplicate values are not added
           to any construction variables; you can specify unique=0 to allow
           duplicate values to be added.

           Interpreted options and the construction variables they affect are
           as specified for the env.ParseFlags method (which this method
           calls). See that method's description, below, for a table of
           options and construction variables.

       ParseDepends(filename, [must_exist, only_one]),
       env.ParseDepends(filename, [must_exist, only_one])
           Parses the contents of the specified filename as a list of
           dependencies in the style of Make or mkdep, and explicitly
           establishes all of the listed dependencies.

           By default, it is not an error if the specified filename does not
           exist. The optional must_exist argument may be set to a non-zero
           value to have scons throw an exception and generate an error if the
           file does not exist, or is otherwise inaccessible.

           The optional only_one argument may be set to a non-zero value to
           have scons thrown an exception and generate an error if the file
           contains dependency information for more than one target. This can
           provide a small sanity check for files intended to be generated by,
           for example, the gcc -M flag, which should typically only write
           dependency information for one output file into a corresponding .d
           file.

           The filename and all of the files listed therein will be
           interpreted relative to the directory of the SConscript file which
           calls the ParseDepends function.

       env.ParseFlags(flags, ...)
           Parses one or more strings containing typical command-line flags
           for GCC tool chains and returns a dictionary with the flag values
           separated into the appropriate SCons construction variables. This
           is intended as a companion to the env.MergeFlags method, but allows
           for the values in the returned dictionary to be modified, if
           necessary, before merging them into the construction environment.
           (Note that env.MergeFlags will call this method if its argument is
           not a dictionary, so it is usually not necessary to call
           env.ParseFlags directly unless you want to manipulate the values.)

           If the first character in any string is an exclamation mark (!),
           the rest of the string is executed as a command, and the output
           from the command is parsed as GCC tool chain command-line flags and
           added to the resulting dictionary.

           Flag values are translated accordig to the prefix found, and added
           to the following construction variables:

               -arch               CCFLAGS, LINKFLAGS
               -D                  CPPDEFINES
               -framework          FRAMEWORKS
               -frameworkdir=      FRAMEWORKPATH
               -include            CCFLAGS
               -isysroot           CCFLAGS, LINKFLAGS
               -I                  CPPPATH
               -l                  LIBS
               -L                  LIBPATH
               -mno-cygwin         CCFLAGS, LINKFLAGS
               -mwindows           LINKFLAGS
               -pthread            CCFLAGS, LINKFLAGS
               -std=               CFLAGS
               -Wa,                ASFLAGS, CCFLAGS
               -Wl,-rpath=         RPATH
               -Wl,-R,             RPATH
               -Wl,-R              RPATH
               -Wl,                LINKFLAGS
               -Wp,                CPPFLAGS
               -                   CCFLAGS
               +                   CCFLAGS, LINKFLAGS

           Any other strings not associated with options are assumed to be the
           names of libraries and added to the $LIBS construction variable.

           Examples (all of which produce the same result):

               dict = env.ParseFlags('-O2 -Dfoo -Dbar=1')
               dict = env.ParseFlags('-O2', '-Dfoo', '-Dbar=1')
               dict = env.ParseFlags(['-O2', '-Dfoo -Dbar=1'])
               dict = env.ParseFlags('-O2', '!echo -Dfoo -Dbar=1')

       env.Perforce()
           A factory function that returns a Builder object to be used to
           fetch source files from the Perforce source code management system.
           The returned Builder is intended to be passed to the SourceCode
           function.

           This function is deprecated. For details, see the entry for the
           SourceCode function.

           Example:

               env.SourceCode('.', env.Perforce())

           Perforce uses a number of external environment variables for its
           operation. Consequently, this function adds the following variables
           from the user's external environment to the construction
           environment's ENV dictionary: P4CHARSET, P4CLIENT, P4LANGUAGE,
           P4PASSWD, P4PORT, P4USER, SystemRoot, USER, and USERNAME.

       Platform(string)
           The Platform form returns a callable object that can be used to
           initialize a construction environment using the platform keyword of
           the Environment function.

           Example:

               env = Environment(platform = Platform('win32'))

           The env.Platform form applies the callable object for the specified
           platform string to the environment through which the method was
           called.

               env.Platform('posix')

           Note that the win32 platform adds the SystemDrive and SystemRoot
           variables from the user's external environment to the construction
           environment's $ENV dictionary. This is so that any executed
           commands that use sockets to connect with other systems (such as
           fetching source files from external CVS repository specifications
           like :pserver:anonymous@cvs.sourceforge.net:/cvsroot/scons) will
           work on Windows systems.

       Precious(target, ...), env.Precious(target, ...)
           Marks each given target as precious so it is not deleted before it
           is rebuilt. Normally scons deletes a target before building it.
           Multiple targets can be passed in to a single call to Precious.

       env.Prepend(key=val, [...])
           Appends the specified keyword arguments to the beginning of
           construction variables in the environment. If the Environment does
           not have the specified construction variable, it is simply added to
           the environment. If the values of the construction variable and the
           keyword argument are the same type, then the two values will be
           simply added together. Otherwise, the construction variable and the
           value of the keyword argument are both coerced to lists, and the
           lists are added together. (See also the Append method, above.)

           Example:

               env.Prepend(CCFLAGS = '-g ', FOO = ['foo.yyy'])

       env.PrependENVPath(name, newpath, [envname, sep, delete_existing])
           This appends new path elements to the given path in the specified
           external environment ($ENV by default). This will only add any
           particular path once (leaving the first one it encounters and
           ignoring the rest, to preserve path order), and to help assure
           this, will normalize all paths (using os.path.normpath and
           os.path.normcase). This can also handle the case where the given
           old path variable is a list instead of a string, in which case a
           list will be returned instead of a string.

           If delete_existing is 0, then adding a path that already exists
           will not move it to the beginning; it will stay where it is in the
           list.

           Example:

               print 'before:',env['ENV']['INCLUDE']
               include_path = '/foo/bar:/foo'
               env.PrependENVPath('INCLUDE', include_path)
               print 'after:',env['ENV']['INCLUDE']

           The above example will print:

               before: /biz:/foo
               after: /foo/bar:/foo:/biz

       env.PrependUnique(key=val, delete_existing=0, [...])
           Appends the specified keyword arguments to the beginning of
           construction variables in the environment. If the Environment does
           not have the specified construction variable, it is simply added to
           the environment. If the construction variable being appended to is
           a list, then any value(s) that already exist in the construction
           variable will not be added again to the list. However, if
           delete_existing is 1, existing matching values are removed first,
           so existing values in the arg list move to the front of the list.

           Example:

               env.PrependUnique(CCFLAGS = '-g', FOO = ['foo.yyy'])

       Progress(callable, [interval]), Progress(string, [interval, file,
       overwrite]), Progress(list_of_strings, [interval, file, overwrite])
           Allows SCons to show progress made during the build by displaying a
           string or calling a function while evaluating Nodes (e.g. files).

           If the first specified argument is a Python callable (a function or
           an object that has a __call__() method), the function will be
           called once every interval times a Node is evaluated. The callable
           will be passed the evaluated Node as its only argument. (For future
           compatibility, it's a good idea to also add *args and **kw as
           arguments to your function or method. This will prevent the code
           from breaking if SCons ever changes the interface to call the
           function with additional arguments in the future.)

           An example of a simple custom progress function that prints a
           string containing the Node name every 10 Nodes:

               def my_progress_function(node, *args, **kw):
                   print 'Evaluating node %s!' % node
               Progress(my_progress_function, interval=10)

           A more complicated example of a custom progress display object that
           prints a string containing a count every 100 evaluated Nodes. Note
           the use of \r (a carriage return) at the end so that the string
           will overwrite itself on a display:

               import sys
               class ProgressCounter(object):
                   count = 0
                   def __call__(self, node, *args, **kw):
                       self.count += 100
                       sys.stderr.write('Evaluated %s nodes\r' % self.count)
               Progress(ProgressCounter(), interval=100)

           If the first argument Progress is a string, the string will be
           displayed every interval evaluated Nodes. The default is to print
           the string on standard output; an alternate output stream may be
           specified with the file= argument. The following will print a
           series of dots on the error output, one dot for every 100 evaluated
           Nodes:

               import sys
               Progress('.', interval=100, file=sys.stderr)

           If the string contains the verbatim substring $TARGET, it will be
           replaced with the Node. Note that, for performance reasons, this is
           not a regular SCons variable substition, so you can not use other
           variables or use curly braces. The following example will print the
           name of every evaluated Node, using a \r (carriage return) to cause
           each line to overwritten by the next line, and the overwrite=
           keyword argument to make sure the previously-printed file name is
           overwritten with blank spaces:

               import sys
               Progress('$TARGET\r', overwrite=True)

           If the first argument to Progress is a list of strings, then each
           string in the list will be displayed in rotating fashion every
           interval evaluated Nodes. This can be used to implement a "spinner"
           on the user's screen as follows:

               Progress(['-\r', '\\\r', '|\r', '/\r'], interval=5)

       Pseudo(target, ...), env.Pseudo(target, ...)
           This indicates that each given target should not be created by the
           build rule, and if the target is created, an error will be
           generated. This is similar to the gnu make .PHONY target. However,
           in the vast majority of cases, an Alias is more appropriate.
           Multiple targets can be passed in to a single call to Pseudo.

       env.RCS()
           A factory function that returns a Builder object to be used to
           fetch source files from RCS. The returned Builder is intended to be
           passed to the SourceCode function:

           This function is deprecated. For details, see the entry for the
           SourceCode function.

           Examples:

               env.SourceCode('.', env.RCS())

           Note that scons will fetch source files from RCS subdirectories
           automatically, so configuring RCS as demonstrated in the above
           example should only be necessary if you are fetching from RCS,v
           files in the same directory as the source files, or if you need to
           explicitly specify RCS for a specific subdirectory.

       env.Replace(key=val, [...])
           Replaces construction variables in the Environment with the
           specified keyword arguments.

           Example:

               env.Replace(CCFLAGS = '-g', FOO = 'foo.xxx')

       Repository(directory), env.Repository(directory)
           Specifies that directory is a repository to be searched for files.
           Multiple calls to Repository are legal, and each one adds to the
           list of repositories that will be searched.

           To scons, a repository is a copy of the source tree, from the
           top-level directory on down, which may contain both source files
           and derived files that can be used to build targets in the local
           source tree. The canonical example would be an official source tree
           maintained by an integrator. If the repository contains derived
           files, then the derived files should have been built using scons,
           so that the repository contains the necessary signature information
           to allow scons to figure out when it is appropriate to use the
           repository copy of a derived file, instead of building one locally.

           Note that if an up-to-date derived file already exists in a
           repository, scons will not make a copy in the local directory tree.
           In order to guarantee that a local copy will be made, use the Local
           method.

       Requires(target, prerequisite), env.Requires(target, prerequisite)
           Specifies an order-only relationship between the specified target
           file(s) and the specified prerequisite file(s). The prerequisite
           file(s) will be (re)built, if necessary, before the target file(s),
           but the target file(s) do not actually depend on the prerequisites
           and will not be rebuilt simply because the prerequisite file(s)
           change.

           Example:

               env.Requires('foo', 'file-that-must-be-built-before-foo')

       Return([vars..., stop=])
           By default, this stops processing the current SConscript file and
           returns to the calling SConscript file the values of the variables
           named in the vars string arguments. Multiple strings contaning
           variable names may be passed to Return. Any strings that contain
           white space

           The optional stop= keyword argument may be set to a false value to
           continue processing the rest of the SConscript file after the
           Return call. This was the default behavior prior to SCons 0.98.
           However, the values returned are still the values of the variables
           in the named vars at the point Return is called.

           Examples:

               # Returns without returning a value.
               Return()

               # Returns the value of the 'foo' Python variable.
               Return("foo")

               # Returns the values of the Python variables 'foo' and 'bar'.
               Return("foo", "bar")

               # Returns the values of Python variables 'val1' and 'val2'.
               Return('val1 val2')

       Scanner(function, [argument, keys, path_function, node_class,
       node_factory, scan_check, recursive]), env.Scanner(function, [argument,
       keys, path_function, node_class, node_factory, scan_check, recursive])
           Creates a Scanner object for the specified function. See the
           section "Scanner Objects," below, for a complete explanation of the
           arguments and behavior.

       env.SCCS()
           A factory function that returns a Builder object to be used to
           fetch source files from SCCS. The returned Builder is intended to
           be passed to the SourceCode function.

           Example:

               env.SourceCode('.', env.SCCS())

           Note that scons will fetch source files from SCCS subdirectories
           automatically, so configuring SCCS as demonstrated in the above
           example should only be necessary if you are fetching from s.SCCS
           files in the same directory as the source files, or if you need to
           explicitly specify SCCS for a specific subdirectory.

       SConscript(scripts, [exports, variant_dir, duplicate]),
       env.SConscript(scripts, [exports, variant_dir, duplicate]),
       SConscript(dirs=subdirs, [name=script, exports, variant_dir,
       duplicate]), env.SConscript(dirs=subdirs, [name=script, exports,
       variant_dir, duplicate])
           This tells scons to execute one or more subsidiary SConscript
           (configuration) files. Any variables returned by a called script
           using Return will be returned by the call to SConscript. There are
           two ways to call the SConscript function.

           The first way you can call SConscript is to explicitly specify one
           or more scripts as the first argument. A single script may be
           specified as a string; multiple scripts must be specified as a list
           (either explicitly or as created by a function like Split).
           Examples:

               SConscript('SConscript')      # run SConscript in the current directory
               SConscript('src/SConscript')  # run SConscript in the src directory
               SConscript(['src/SConscript', 'doc/SConscript'])
               config = SConscript('MyConfig.py')

           The second way you can call SConscript is to specify a list of
           (sub)directory names as a dirs=subdirs keyword argument. In this
           case, scons will, by default, execute a subsidiary configuration
           file named SConscript in each of the specified directories. You may
           specify a name other than SConscript by supplying an optional
           name=script keyword argument. The first three examples below have
           the same effect as the first three examples above:

               SConscript(dirs='.')      # run SConscript in the current directory
               SConscript(dirs='src')    # run SConscript in the src directory
               SConscript(dirs=['src', 'doc'])
               SConscript(dirs=['sub1', 'sub2'], name='MySConscript')

           The optional exports argument provides a list of variable names or
           a dictionary of named values to export to the script(s). These
           variables are locally exported only to the specified script(s), and
           do not affect the global pool of variables used by the Export
           function.  The subsidiary script(s) must use the Import function to
           import the variables. Examples:

               foo = SConscript('sub/SConscript', exports='env')
               SConscript('dir/SConscript', exports=['env', 'variable'])
               SConscript(dirs='subdir', exports='env variable')
               SConscript(dirs=['one', 'two', 'three'], exports='shared_info')

           If the optional variant_dir argument is present, it causes an
           effect equivalent to the VariantDir method described below. (If
           variant_dir is not present, the

           duplicate argument is ignored.) The variant_dir argument is
           interpreted relative to the directory of the calling SConscript
           file. See the description of the VariantDir function below for
           additional details and restrictions.

           If variant_dir is present, the source directory is the directory in
           which the SConscript file resides and the SConscript file is
           evaluated as if it were in the variant_dir directory:

               SConscript('src/SConscript', variant_dir = 'build')

           is equivalent to

               VariantDir('build', 'src')
               SConscript('build/SConscript')

           This later paradigm is often used when the sources are in the same
           directory as the SConstruct:

               SConscript('SConscript', variant_dir = 'build')

           is equivalent to

               VariantDir('build', '.')
               SConscript('build/SConscript')



           Here are some composite examples:

               # collect the configuration information and use it to build src and doc
               shared_info = SConscript('MyConfig.py')
               SConscript('src/SConscript', exports='shared_info')
               SConscript('doc/SConscript', exports='shared_info')

               # build debugging and production versions.  SConscript
               # can use Dir('.').path to determine variant.
               SConscript('SConscript', variant_dir='debug', duplicate=0)
               SConscript('SConscript', variant_dir='prod', duplicate=0)

               # build debugging and production versions.  SConscript
               # is passed flags to use.
               opts = { 'CPPDEFINES' : ['DEBUG'], 'CCFLAGS' : '-pgdb' }
               SConscript('SConscript', variant_dir='debug', duplicate=0, exports=opts)
               opts = { 'CPPDEFINES' : ['NODEBUG'], 'CCFLAGS' : '-O' }
               SConscript('SConscript', variant_dir='prod', duplicate=0, exports=opts)

               # build common documentation and compile for different architectures
               SConscript('doc/SConscript', variant_dir='build/doc', duplicate=0)
               SConscript('src/SConscript', variant_dir='build/x86', duplicate=0)
               SConscript('src/SConscript', variant_dir='build/ppc', duplicate=0)

       SConscriptChdir(value), env.SConscriptChdir(value)
           By default, scons changes its working directory to the directory in
           which each subsidiary SConscript file lives. This behavior may be
           disabled by specifying either:

               SConscriptChdir(0)
               env.SConscriptChdir(0)

           in which case scons will stay in the top-level directory while
           reading all SConscript files. (This may be necessary when building
           from repositories, when all the directories in which SConscript
           files may be found don't necessarily exist locally.) You may enable
           and disable this ability by calling SConscriptChdir() multiple
           times.

           Example:

               env = Environment()
               SConscriptChdir(0)
               SConscript('foo/SConscript')  # will not chdir to foo
               env.SConscriptChdir(1)
               SConscript('bar/SConscript')  # will chdir to bar

       SConsignFile([file, dbm_module]), env.SConsignFile([file, dbm_module])
           This tells scons to store all file signatures in the specified
           database file. If the file name is omitted, .sconsign is used by
           default. (The actual file name(s) stored on disk may have an
           appropriated suffix appended by the
            dbm_module.) If file is not an absolute path name, the file is
           placed in the same directory as the top-level SConstruct file.

           If file is None, then scons will store file signatures in a
           separate .sconsign file in each directory, not in one global
           database file. (This was the default behavior prior to SCons
           0.96.91 and 0.97.)

           The optional dbm_module argument can be used to specify which
           Python database module The default is to use a custom SCons.dblite
           module that uses pickled Python data structures, and which works on
           all Python versions.

           Examples:

               # Explicitly stores signatures in ".sconsign.dblite"
               # in the top-level SConstruct directory (the
               # default behavior).
               SConsignFile()

               # Stores signatures in the file "etc/scons-signatures"
               # relative to the top-level SConstruct directory.
               SConsignFile("etc/scons-signatures")

               # Stores signatures in the specified absolute file name.
               SConsignFile("/home/me/SCons/signatures")

               # Stores signatures in a separate .sconsign file
               # in each directory.
               SConsignFile(None)

       env.SetDefault(key=val, [...])
           Sets construction variables to default values specified with the
           keyword arguments if (and only if) the variables are not already
           set. The following statements are equivalent:

               env.SetDefault(FOO = 'foo')

               if 'FOO' not in env: env['FOO'] = 'foo'

       SetOption(name, value), env.SetOption(name, value)
           This function provides a way to set a select subset of the scons
           command line options from a SConscript file. The options supported
           are:

           clean
               which corresponds to -c, --clean and --remove;

           duplicate
               which corresponds to --duplicate;

           help
               which corresponds to -h and --help;

           implicit_cache
               which corresponds to --implicit-cache;

           max_drift
               which corresponds to --max-drift;

           no_exec
               which corresponds to -n, --no-exec, --just-print, --dry-run and
               --recon;

           num_jobs
               which corresponds to -j and --jobs;

           random
               which corresponds to --random; and

           stack_size
               which corresponds to --stack-size.

           See the documentation for the corresponding command line object for
           information about each specific option.

           Example:

               SetOption('max_drift', 1)

       SideEffect(side_effect, target), env.SideEffect(side_effect, target)
           Declares side_effect as a side effect of building target. Both
           side_effect and target can be a list, a file name, or a node. A
           side effect is a target file that is created or updated as a side
           effect of building other targets. For example, a Windows PDB file
           is created as a side effect of building the .obj files for a static
           library, and various log files are created updated as side effects
           of various TeX commands. If a target is a side effect of multiple
           build commands, scons will ensure that only one set of commands is
           executed at a time. Consequently, you only need to use this method
           for side-effect targets that are built as a result of multiple
           build commands.

           Because multiple build commands may update the same side effect
           file, by default the side_effect target is not automatically
           removed when the target is removed by the -c option. (Note,
           however, that the side_effect might be removed as part of cleaning
           the directory in which it lives.) If you want to make sure the
           side_effect is cleaned whenever a specific target is cleaned, you
           must specify this explicitly with the Clean or env.Clean function.

       SourceCode(entries, builder), env.SourceCode(entries, builder)
           This function and its associate factory functions are deprecated.
           There is no replacement. The intended use was to keep a local tree
           in sync with an archive, but in actuality the function only causes
           the archive to be fetched on the first run. Synchronizing with the
           archive is best done external to SCons.

           Arrange for non-existent source files to be fetched from a source
           code management system using the specified builder. The specified
           entries may be a Node, string or list of both, and may represent
           either individual source files or directories in which source files
           can be found.

           For any non-existent source files, scons will search up the
           directory tree and use the first SourceCode builder it finds. The
           specified builder may be None, in which case scons will not use a
           builder to fetch source files for the specified entries, even if a
           SourceCode builder has been specified for a directory higher up the
           tree.


           scons will, by default, fetch files from SCCS or RCS subdirectories
           without explicit configuration. This takes some extra processing
           time to search for the necessary source code management files on
           disk. You can avoid these extra searches and speed up your build a
           little by disabling these searches as follows:

               env.SourceCode('.', None)

           Note that if the specified builder is one you create by hand, it
           must have an associated construction environment to use when
           fetching a source file.


           scons provides a set of canned factory functions that return
           appropriate Builders for various popular source code management
           systems. Canonical examples of invocation include:

               env.SourceCode('.', env.BitKeeper('/usr/local/BKsources'))
               env.SourceCode('src', env.CVS('/usr/local/CVSROOT'))
               env.SourceCode('/', env.RCS())
               env.SourceCode(['f1.c', 'f2.c'], env.SCCS())
               env.SourceCode('no_source.c', None)



       SourceSignatures(type), env.SourceSignatures(type)
           Note: Although it is not yet officially deprecated, use of this
           function is discouraged. See the Decider function for a more
           flexible and straightforward way to configure SCons'
           decision-making.

           The SourceSignatures function tells scons how to decide if a source
           file (a file that is not built from any other files) has changed
           since the last time it was used to build a particular target file.
           Legal values are MD5 or timestamp.

           If the environment method is used, the specified type of source
           signature is only used when deciding whether targets built with
           that environment are up-to-date or must be rebuilt. If the global
           function is used, the specified type of source signature becomes
           the default used for all decisions about whether targets are
           up-to-date.


           MD5 means scons decides that a source file has changed if the MD5
           checksum of its contents has changed since the last time it was
           used to rebuild a particular target file.


           timestamp means scons decides that a source file has changed if its
           timestamp (modification time) has changed since the last time it
           was used to rebuild a particular target file. (Note that although
           this is similar to the behavior of Make, by default it will also
           rebuild if the dependency is older than the last time it was used
           to rebuild the target file.)

           There is no different between the two behaviors for Python Value
           node objects.


           MD5 signatures take longer to compute, but are more accurate than
           timestamp signatures. The default value is MD5.

           Note that the default TargetSignatures setting (see below) is to
           use this SourceSignatures setting for any target files that are
           used to build other target files. Consequently, changing the value
           of SourceSignatures will, by default, affect the up-to-date
           decision for all files in the build (or all files built with a
           specific construction environment when env.SourceSignatures is
           used).

       Split(arg), env.Split(arg)
           Returns a list of file names or other objects. If arg is a string,
           it will be split on strings of white-space characters within the
           string, making it easier to write long lists of file names. If arg
           is already a list, the list will be returned untouched. If arg is
           any other type of object, it will be returned as a list containing
           just the object.

           Example:

               files = Split("f1.c f2.c f3.c")
               files = env.Split("f4.c f5.c f6.c")
               files = Split("""
                    f7.c
                    f8.c
                    f9.c
               """)

       env.subst(input, [raw, target, source, conv])
           Performs construction variable interpolation on the specified
           string or sequence argument input.

           By default, leading or trailing white space will be removed from
           the result. and all sequences of white space will be compressed to
           a single space character. Additionally, any $( and $) character
           sequences will be stripped from the returned string, The optional
           raw argument may be set to 1 if you want to preserve white space
           and $(-$) sequences. The raw argument may be set to 2 if you want
           to strip all characters between any $( and $) pairs (as is done for
           signature calculation).

           If the input is a sequence (list or tuple), the individual elements
           of the sequence will be expanded, and the results will be returned
           as a list.

           The optional target and source keyword arguments must be set to
           lists of target and source nodes, respectively, if you want the
           $TARGET, $TARGETS, $SOURCE and $SOURCES to be available for
           expansion. This is usually necessary if you are calling env.subst
           from within a Python function used as an SCons action.

           Returned string values or sequence elements are converted to their
           string representation by default. The optional conv argument may
           specify a conversion function that will be used in place of the
           default. For example, if you want Python objects (including SCons
           Nodes) to be returned as Python objects, you can use the Python
           idiom to pass in an unnamed function that simply returns its
           unconverted argument.

           Example:

               print env.subst("The C compiler is: $CC")

               def compile(target, source, env):
                   sourceDir = env.subst("${SOURCE.srcdir}",
                                         target=target,
                                         source=source)

               source_nodes = env.subst('$EXPAND_TO_NODELIST',
                                        conv=lambda x: x)

       Tag(node, tags)
           Annotates file or directory Nodes with information about how the
           Package Builder should package those files or directories. All tags
           are optional.

           Examples:

               # makes sure the built library will be installed with 0644 file
               # access mode
               Tag( Library( 'lib.c' ), UNIX_ATTR="0644" )

               # marks file2.txt to be a documentation file
               Tag( 'file2.txt', DOC )

       TargetSignatures(type), env.TargetSignatures(type)
           Note: Although it is not yet officially deprecated, use of this
           function is discouraged. See the Decider function for a more
           flexible and straightforward way to configure SCons'
           decision-making.

           The TargetSignatures function tells scons how to decide if a target
           file (a file that is built from any other files) has changed since
           the last time it was used to build some other target file. Legal
           values are "build"; "content" (or its synonym "MD5"); "timestamp";
           or "source".

           If the environment method is used, the specified type of target
           signature is only used for targets built with that environment. If
           the global function is used, the specified type of signature
           becomes the default used for all target files that don't have an
           explicit target signature type specified for their environments.


           "content" (or its synonym "MD5") means scons decides that a target
           file has changed if the MD5 checksum of its contents has changed
           since the last time it was used to rebuild some other target file.
           This means scons will open up MD5 sum the contents of target files
           after they're built, and may decide that it does not need to
           rebuild "downstream" target files if a file was rebuilt with
           exactly the same contents as the last time.


           "timestamp" means scons decides that a target file has changed if
           its timestamp (modification time) has changed since the last time
           it was used to rebuild some other target file. (Note that although
           this is similar to the behavior of Make, by default it will also
           rebuild if the dependency is older than the last time it was used
           to rebuild the target file.)


           "source" means scons decides that a target file has changed as
           specified by the corresponding SourceSignatures setting ("MD5" or
           "timestamp"). This means that scons will treat all input files to a
           target the same way, regardless of whether they are source files or
           have been built from other files.


           "build" means scons decides that a target file has changed if it
           has been rebuilt in this invocation or if its content or timestamp
           have changed as specified by the corresponding SourceSignatures
           setting. This "propagates" the status of a rebuilt file so that
           other "downstream" target files will always be rebuilt, even if the
           contents or the timestamp have not changed.


           "build" signatures are fastest because "content" (or "MD5")
           signatures take longer to compute, but are more accurate than
           "timestamp" signatures, and can prevent unnecessary "downstream"
           rebuilds when a target file is rebuilt to the exact same contents
           as the previous build. The "source" setting provides the most
           consistent behavior when other target files may be rebuilt from
           both source and target input files. The default value is "source".

           Because the default setting is "source", using SourceSignatures is
           generally preferable to TargetSignatures, so that the up-to-date
           decision will be consistent for all files (or all files built with
           a specific construction environment). Use of TargetSignatures
           provides specific control for how built target files affect their
           "downstream" dependencies.

       Tool(string, [toolpath, **kw]), env.Tool(string, [toolpath, **kw])
           The Tool form of the function returns a callable object that can be
           used to initialize a construction environment using the tools
           keyword of the Environment() method. The object may be called with
           a construction environment as an argument, in which case the object
           will add the necessary variables to the construction environment
           and the name of the tool will be added to the $TOOLS construction
           variable.

           Additional keyword arguments are passed to the tool's generate()
           method.

           Examples:

               env = Environment(tools = [ Tool('msvc') ])

               env = Environment()
               t = Tool('msvc')
               t(env)  # adds 'msvc' to the TOOLS variable
               u = Tool('opengl', toolpath = ['tools'])
               u(env)  # adds 'opengl' to the TOOLS variable

           The env.Tool form of the function applies the callable object for
           the specified tool string to the environment through which the
           method was called.

           Additional keyword arguments are passed to the tool's generate()
           method.

               env.Tool('gcc')
               env.Tool('opengl', toolpath = ['build/tools'])

       Value(value, [built_value]), env.Value(value, [built_value])
           Returns a Node object representing the specified Python value.
           Value Nodes can be used as dependencies of targets. If the result
           of calling str(value) changes between SCons runs, any targets
           depending on Value(value) will be rebuilt. (This is true even when
           using timestamps to decide if files are up-to-date.) When using
           timestamp source signatures, Value Nodes' timestamps are equal to
           the system time when the Node is created.

           The returned Value Node object has a write() method that can be
           used to "build" a Value Node by setting a new value. The optional
           built_value argument can be specified when the Value Node is
           created to indicate the Node should already be considered "built."
           There is a corresponding read() method that will return the built
           value of the Node.

           Examples:

               env = Environment()

               def create(target, source, env):
                   # A function that will write a 'prefix=$SOURCE'
                   # string into the file name specified as the
                   # $TARGET.
                   f = open(str(target[0]), 'wb')
                   f.write('prefix=' + source[0].get_contents())

               # Fetch the prefix= argument, if any, from the command
               # line, and use /usr/local as the default.
               prefix = ARGUMENTS.get('prefix', '/usr/local')

               # Attach a .Config() builder for the above function action
               # to the construction environment.
               env['BUILDERS']['Config'] = Builder(action = create)
               env.Config(target = 'package-config', source = Value(prefix))

               def build_value(target, source, env):
                   # A function that "builds" a Python Value by updating
                   # the the Python value with the contents of the file
                   # specified as the source of the Builder call ($SOURCE).
                   target[0].write(source[0].get_contents())

               output = env.Value('before')
               input = env.Value('after')

               # Attach a .UpdateValue() builder for the above function
               # action to the construction environment.
               env['BUILDERS']['UpdateValue'] = Builder(action = build_value)
               env.UpdateValue(target = Value(output), source = Value(input))

       VariantDir(variant_dir, src_dir, [duplicate]),
       env.VariantDir(variant_dir, src_dir, [duplicate])
           Use the VariantDir function to create a copy of your sources in
           another location: if a name under variant_dir is not found but
           exists under src_dir, the file or directory is copied to
           variant_dir. Target files can be built in a different directory
           than the original sources by simply refering to the sources (and
           targets) within the variant tree.


           VariantDir can be called multiple times with the same src_dir to
           set up multiple builds with different options (variants). The
           src_dir location must be in or underneath the SConstruct file's
           directory, and variant_dir may not be underneath src_dir.

           The default behavior is for scons to physically duplicate the
           source files in the variant tree. Thus, a build performed in the
           variant tree is guaranteed to be identical to a build performed in
           the source tree even if intermediate source files are generated
           during the build, or preprocessors or other scanners search for
           included files relative to the source file, or individual compilers
           or other invoked tools are hard-coded to put derived files in the
           same directory as source files.

           If possible on the platform, the duplication is performed by
           linking rather than copying; see also the --duplicate command-line
           option. Moreover, only the files needed for the build are
           duplicated; files and directories that are not used are not present
           in variant_dir.

           Duplicating the source tree may be disabled by setting the
           duplicate argument to 0 (zero). This will cause scons to invoke
           Builders using the path names of source files in src_dir and the
           path names of derived files within variant_dir. This is always more
           efficient than duplicate=1, and is usually safe for most builds
           (but see above for cases that may cause problems).

           Note that VariantDir works most naturally with a subsidiary
           SConscript file. However, you would then call the subsidiary
           SConscript file not in the source directory, but in the
           variant_dir, regardless of the value of duplicate. This is how you
           tell scons which variant of a source tree to build:

               # run src/SConscript in two variant directories
               VariantDir('build/variant1', 'src')
               SConscript('build/variant1/SConscript')
               VariantDir('build/variant2', 'src')
               SConscript('build/variant2/SConscript')

           See also the SConscript function, described above, for another way
           to specify a variant directory in conjunction with calling a
           subsidiary SConscript file.

           Examples:

               # use names in the build directory, not the source directory
               VariantDir('build', 'src', duplicate=0)
               Program('build/prog', 'build/source.c')

               # this builds both the source and docs in a separate subtree
               VariantDir('build', '.', duplicate=0)
               SConscript(dirs=['build/src','build/doc'])

               # same as previous example, but only uses SConscript
               SConscript(dirs='src', variant_dir='build/src', duplicate=0)
               SConscript(dirs='doc', variant_dir='build/doc', duplicate=0)

       WhereIs(program, [path, pathext, reject]), env.WhereIs(program, [path,
       pathext, reject])
           Searches for the specified executable program, returning the full
           path name to the program if it is found, and returning None if not.
           Searches the specified path, the value of the calling environment's
           PATH (env['ENV']['PATH']), or the user's current external PATH
           (os.environ['PATH']) by default. On Windows systems, searches for
           executable programs with any of the file extensions listed in the
           specified pathext, the calling environment's PATHEXT
           (env['ENV']['PATHEXT']) or the user's current PATHEXT
           (os.environ['PATHEXT']) by default. Will not select any path name
           or names in the specified reject list, if any.

   SConscript Variables
       In addition to the global functions and methods, scons supports a
       number of Python variables that can be used in SConscript files to
       affect how you want the build to be performed. These variables may be
       accessed from custom Python modules that you import into an SConscript
       file by adding the following to the Python module:

           from SCons.Script import *

       ARGLIST
           A list keyword=value arguments specified on the command line. Each
           element in the list is a tuple containing the (keyword,value) of
           the argument. The separate keyword and value elements of the tuple
           can be accessed by subscripting for element [0] and [1] of the
           tuple, respectively.

           Example:

               print "first keyword, value =", ARGLIST[0][0], ARGLIST[0][1]
               print "second keyword, value =", ARGLIST[1][0], ARGLIST[1][1]
               third_tuple = ARGLIST[2]
               print "third keyword, value =", third_tuple[0], third_tuple[1]
               for key, value in ARGLIST:
                   # process key and value

       ARGUMENTS
           A dictionary of all the keyword=value arguments specified on the
           command line. The dictionary is not in order, and if a given
           keyword has more than one value assigned to it on the command line,
           the last (right-most) value is the one in the ARGUMENTS dictionary.

           Example:

               if ARGUMENTS.get('debug', 0):
                   env = Environment(CCFLAGS = '-g')
               else:
                   env = Environment()

       BUILD_TARGETS
           A list of the targets which scons will actually try to build,
           regardless of whether they were specified on the command line or
           via the Default() function or method. The elements of this list may
           be strings or nodes, so you should run the list through the Python
           str function to make sure any Node path names are converted to
           strings.

           Because this list may be taken from the list of targets specified
           using the Default() function or method, the contents of the list
           may change on each successive call to Default(). See the
           DEFAULT_TARGETS list, below, for additional information.

           Example:

               if 'foo' in BUILD_TARGETS:
                   print "Don't forget to test the `foo' program!"
               if 'special/program' in BUILD_TARGETS:
                   SConscript('special')

       Note that the BUILD_TARGETS list only contains targets expected listed
       on the command line or via calls to the Default() function or method.
       It does not contain all dependent targets that will be built as a
       result of making the sure the explicitly-specified targets are up to
       date.

       COMMAND_LINE_TARGETS
           A list of the targets explicitly specified on the command line. If
           there are no targets specified on the command line, the list is
           empty. This can be used, for example, to take specific actions only
           when a certain target or targets is explicitly being built.

           Example:

               if 'foo' in COMMAND_LINE_TARGETS:
                   print "Don't forget to test the `foo' program!"
               if 'special/program' in COMMAND_LINE_TARGETS:
                   SConscript('special')

       DEFAULT_TARGETS
           A list of the target nodes that have been specified using the
           Default() function or method. The elements of the list are nodes,
           so you need to run them through the Python str function to get at
           the path name for each Node.

           Example:

               print str(DEFAULT_TARGETS[0])
               if 'foo' in map(str, DEFAULT_TARGETS):
                   print "Don't forget to test the `foo' program!"

       The contents of the DEFAULT_TARGETS list change on on each successive
       call to the Default() function:

           print map(str, DEFAULT_TARGETS)   # originally []
           Default('foo')
           print map(str, DEFAULT_TARGETS)   # now a node ['foo']
           Default('bar')
           print map(str, DEFAULT_TARGETS)   # now a node ['foo', 'bar']
           Default(None)
           print map(str, DEFAULT_TARGETS)   # back to []

       Consequently, be sure to use DEFAULT_TARGETS only after you've made all
       of your Default() calls, or else simply be careful of the order of
       these statements in your SConscript files so that you don't look for a
       specific default target before it's actually been added to the list.

   Construction Variables
       A construction environment has an associated dictionary of construction
       variables that are used by built-in or user-supplied build rules.
       Construction variables must follow the same rules for Python
       identifiers: the initial character must be an underscore or letter,
       followed by any number of underscores, letters, or digits.

       A number of useful construction variables are automatically defined by
       scons for each supported platform, and additional construction
       variables can be defined by the user. The following is a list of the
       automatically defined construction variables:

       __LDMODULEVERSIONFLAGS
           This construction variable automatically introduces
           $_LDMODULEVERSIONFLAGS if $LDMODULEVERSION is set. Othervise it
           evaluates to an empty string.

       __SHLIBVERSIONFLAGS
           This construction variable automatically introduces
           $_SHLIBVERSIONFLAGS if $SHLIBVERSION is set. Othervise it evaluates
           to an empty string.

       AR
           The static library archiver.

       ARCHITECTURE
           Specifies the system architecture for which the package is being
           built. The default is the system architecture of the machine on
           which SCons is running. This is used to fill in the Architecture:
           field in an Ipkg control file, and as part of the name of a
           generated RPM file.

       ARCOM
           The command line used to generate a static library from object
           files.

       ARCOMSTR
           The string displayed when an object file is generated from an
           assembly-language source file. If this is not set, then $ARCOM (the
           command line) is displayed.

               env = Environment(ARCOMSTR = "Archiving $TARGET")

       ARFLAGS
           General options passed to the static library archiver.

       AS
           The assembler.

       ASCOM
           The command line used to generate an object file from an
           assembly-language source file.

       ASCOMSTR
           The string displayed when an object file is generated from an
           assembly-language source file. If this is not set, then $ASCOM (the
           command line) is displayed.

               env = Environment(ASCOMSTR = "Assembling $TARGET")

       ASFLAGS
           General options passed to the assembler.

       ASPPCOM
           The command line used to assemble an assembly-language source file
           into an object file after first running the file through the C
           preprocessor. Any options specified in the $ASFLAGS and $CPPFLAGS
           construction variables are included on this command line.

       ASPPCOMSTR
           The string displayed when an object file is generated from an
           assembly-language source file after first running the file through
           the C preprocessor. If this is not set, then $ASPPCOM (the command
           line) is displayed.

               env = Environment(ASPPCOMSTR = "Assembling $TARGET")

       ASPPFLAGS
           General options when an assembling an assembly-language source file
           into an object file after first running the file through the C
           preprocessor. The default is to use the value of $ASFLAGS.

       BIBTEX
           The bibliography generator for the TeX formatter and typesetter and
           the LaTeX structured formatter and typesetter.

       BIBTEXCOM
           The command line used to call the bibliography generator for the
           TeX formatter and typesetter and the LaTeX structured formatter and
           typesetter.

       BIBTEXCOMSTR
           The string displayed when generating a bibliography for TeX or
           LaTeX. If this is not set, then $BIBTEXCOM (the command line) is
           displayed.

               env = Environment(BIBTEXCOMSTR = "Generating bibliography $TARGET")

       BIBTEXFLAGS
           General options passed to the bibliography generator for the TeX
           formatter and typesetter and the LaTeX structured formatter and
           typesetter.

       BITKEEPER
           The BitKeeper executable.

       BITKEEPERCOM
           The command line for fetching source files using BitKeeper.

       BITKEEPERCOMSTR
           The string displayed when fetching a source file using BitKeeper.
           If this is not set, then $BITKEEPERCOM (the command line) is
           displayed.

       BITKEEPERGET
           The command ($BITKEEPER) and subcommand for fetching source files
           using BitKeeper.

       BITKEEPERGETFLAGS
           Options that are passed to the BitKeeper get subcommand.

       BUILDERS
           A dictionary mapping the names of the builders available through
           this environment to underlying Builder objects. Builders named
           Alias, CFile, CXXFile, DVI, Library, Object, PDF, PostScript, and
           Program are available by default. If you initialize this variable
           when an Environment is created:

               env = Environment(BUILDERS = {'NewBuilder' : foo})

           the default Builders will no longer be available. To use a new
           Builder object in addition to the default Builders, add your new
           Builder object like this:

               env = Environment()
               env.Append(BUILDERS = {'NewBuilder' : foo})

           or this:

               env = Environment()
               env['BUILDERS]['NewBuilder'] = foo

       CC
           The C compiler.

       CCCOM
           The command line used to compile a C source file to a (static)
           object file. Any options specified in the $CFLAGS, $CCFLAGS and
           $CPPFLAGS construction variables are included on this command line.

       CCCOMSTR
           The string displayed when a C source file is compiled to a (static)
           object file. If this is not set, then $CCCOM (the command line) is
           displayed.

               env = Environment(CCCOMSTR = "Compiling static object $TARGET")

       CCFLAGS
           General options that are passed to the C and C++ compilers.

       CCPCHFLAGS
           Options added to the compiler command line to support building with
           precompiled headers. The default value expands expands to the
           appropriate Microsoft Visual C++ command-line options when the $PCH
           construction variable is set.

       CCPDBFLAGS
           Options added to the compiler command line to support storing
           debugging information in a Microsoft Visual C++ PDB file. The
           default value expands expands to appropriate Microsoft Visual C++
           command-line options when the $PDB construction variable is set.

           The Visual C++ compiler option that SCons uses by default to
           generate PDB information is /Z7. This works correctly with parallel
           (-j) builds because it embeds the debug information in the
           intermediate object files, as opposed to sharing a single PDB file
           between multiple object files. This is also the only way to get
           debug information embedded into a static library. Using the /Zi
           instead may yield improved link-time performance, although parallel
           builds will no longer work.

           You can generate PDB files with the /Zi switch by overriding the
           default $CCPDBFLAGS variable as follows:

               env['CCPDBFLAGS'] = ['${(PDB and "/Zi /Fd%s" % File(PDB)) or ""}']

           An alternative would be to use the /Zi to put the debugging
           information in a separate .pdb file for each object file by
           overriding the $CCPDBFLAGS variable as follows:

               env['CCPDBFLAGS'] = '/Zi /Fd${TARGET}.pdb'

       CCVERSION
           The version number of the C compiler. This may or may not be set,
           depending on the specific C compiler being used.

       CFILESUFFIX
           The suffix for C source files. This is used by the internal CFile
           builder when generating C files from Lex (.l) or YACC (.y) input
           files. The default suffix, of course, is .c (lower case). On
           case-insensitive systems (like Windows), SCons also treats .C
           (upper case) files as C files.

       CFLAGS
           General options that are passed to the C compiler (C only; not
           C++).

       CHANGE_SPECFILE
           A hook for modifying the file that controls the packaging build
           (the .spec for RPM, the control for Ipkg, the .wxs for MSI). If
           set, the function will be called after the SCons template for the
           file has been written. XXX

       CHANGED_SOURCES
           A reserved variable name that may not be set or used in a
           construction environment. (See "Variable Substitution," below.)

       CHANGED_TARGETS
           A reserved variable name that may not be set or used in a
           construction environment. (See "Variable Substitution," below.)

       CHANGELOG
           The name of a file containing the change log text to be included in
           the package. This is included as the %changelog section of the RPM
           .spec file.

       _concat
           A function used to produce variables like $_CPPINCFLAGS. It takes
           four or five arguments: a prefix to concatenate onto each element,
           a list of elements, a suffix to concatenate onto each element, an
           environment for variable interpolation, and an optional function
           that will be called to transform the list before concatenation.

               env['_CPPINCFLAGS'] = '$( ${_concat(INCPREFIX, CPPPATH, INCSUFFIX, __env__, RDirs)} $)',

       CONFIGUREDIR
           The name of the directory in which Configure context test files are
           written. The default is .sconf_temp in the top-level directory
           containing the SConstruct file.

       CONFIGURELOG
           The name of the Configure context log file. The default is
           config.log in the top-level directory containing the SConstruct
           file.

       _CPPDEFFLAGS
           An automatically-generated construction variable containing the C
           preprocessor command-line options to define values. The value of
           $_CPPDEFFLAGS is created by appending $CPPDEFPREFIX and
           $CPPDEFSUFFIX to the beginning and end of each definition in
           $CPPDEFINES.

       CPPDEFINES
           A platform independent specification of C preprocessor definitions.
           The definitions will be added to command lines through the
           automatically-generated $_CPPDEFFLAGS construction variable (see
           above), which is constructed according to the type of value of
           $CPPDEFINES:

           If $CPPDEFINES is a string, the values of the $CPPDEFPREFIX and
           $CPPDEFSUFFIX construction variables will be added to the beginning
           and end.

               # Will add -Dxyz to POSIX compiler command lines,
               # and /Dxyz to Microsoft Visual C++ command lines.
               env = Environment(CPPDEFINES='xyz')

           If $CPPDEFINES is a list, the values of the $CPPDEFPREFIX and
           $CPPDEFSUFFIX construction variables will be appended to the
           beginning and end of each element in the list. If any element is a
           list or tuple, then the first item is the name being defined and
           the second item is its value:

               # Will add -DB=2 -DA to POSIX compiler command lines,
               # and /DB=2 /DA to Microsoft Visual C++ command lines.
               env = Environment(CPPDEFINES=[('B', 2), 'A'])

           If $CPPDEFINES is a dictionary, the values of the $CPPDEFPREFIX and
           $CPPDEFSUFFIX construction variables will be appended to the
           beginning and end of each item from the dictionary. The key of each
           dictionary item is a name being defined to the dictionary item's
           corresponding value; if the value is None, then the name is defined
           without an explicit value. Note that the resulting flags are sorted
           by keyword to ensure that the order of the options on the command
           line is consistent each time scons is run.

               # Will add -DA -DB=2 to POSIX compiler command lines,
               # and /DA /DB=2 to Microsoft Visual C++ command lines.
               env = Environment(CPPDEFINES={'B':2, 'A':None})

       CPPDEFPREFIX
           The prefix used to specify preprocessor definitions on the C
           compiler command line. This will be appended to the beginning of
           each definition in the $CPPDEFINES construction variable when the
           $_CPPDEFFLAGS variable is automatically generated.

       CPPDEFSUFFIX
           The suffix used to specify preprocessor definitions on the C
           compiler command line. This will be appended to the end of each
           definition in the $CPPDEFINES construction variable when the
           $_CPPDEFFLAGS variable is automatically generated.

       CPPFLAGS
           User-specified C preprocessor options. These will be included in
           any command that uses the C preprocessor, including not just
           compilation of C and C++ source files via the $CCCOM, $SHCCCOM,
           $CXXCOM and $SHCXXCOM command lines, but also the $FORTRANPPCOM,
           $SHFORTRANPPCOM, $F77PPCOM and $SHF77PPCOM command lines used to
           compile a Fortran source file, and the $ASPPCOM command line used
           to assemble an assembly language source file, after first running
           each file through the C preprocessor. Note that this variable does
           not contain -I (or similar) include search path options that scons
           generates automatically from $CPPPATH. See $_CPPINCFLAGS, below,
           for the variable that expands to those options.

       _CPPINCFLAGS
           An automatically-generated construction variable containing the C
           preprocessor command-line options for specifying directories to be
           searched for include files. The value of $_CPPINCFLAGS is created
           by appending $INCPREFIX and $INCSUFFIX to the beginning and end of
           each directory in $CPPPATH.

       CPPPATH
           The list of directories that the C preprocessor will search for
           include directories. The C/C++ implicit dependency scanner will
           search these directories for include files. Don't explicitly put
           include directory arguments in CCFLAGS or CXXFLAGS because the
           result will be non-portable and the directories will not be
           searched by the dependency scanner. Note: directory names in
           CPPPATH will be looked-up relative to the SConscript directory when
           they are used in a command. To force scons to look-up a directory
           relative to the root of the source tree use #:

               env = Environment(CPPPATH='#/include')

           The directory look-up can also be forced using the Dir() function:

               include = Dir('include')
               env = Environment(CPPPATH=include)

           The directory list will be added to command lines through the
           automatically-generated $_CPPINCFLAGS construction variable, which
           is constructed by appending the values of the $INCPREFIX and
           $INCSUFFIX construction variables to the beginning and end of each
           directory in $CPPPATH. Any command lines you define that need the
           CPPPATH directory list should include $_CPPINCFLAGS:

               env = Environment(CCCOM="my_compiler $_CPPINCFLAGS -c -o $TARGET $SOURCE")

       CPPSUFFIXES
           The list of suffixes of files that will be scanned for C
           preprocessor implicit dependencies (#include lines). The default
           list is:

               [".c", ".C", ".cxx", ".cpp", ".c++", ".cc",
                ".h", ".H", ".hxx", ".hpp", ".hh",
                ".F", ".fpp", ".FPP",
                ".m", ".mm",
                ".S", ".spp", ".SPP"]

       CVS
           The CVS executable.

       CVSCOFLAGS
           Options that are passed to the CVS checkout subcommand.

       CVSCOM
           The command line used to fetch source files from a CVS repository.

       CVSCOMSTR
           The string displayed when fetching a source file from a CVS
           repository. If this is not set, then $CVSCOM (the command line) is
           displayed.

       CVSFLAGS
           General options that are passed to CVS. By default, this is set to
           -d $CVSREPOSITORY to specify from where the files must be fetched.

       CVSREPOSITORY
           The path to the CVS repository. This is referenced in the default
           $CVSFLAGS value.

       CXX
           The C++ compiler.

       CXXCOM
           The command line used to compile a C++ source file to an object
           file. Any options specified in the $CXXFLAGS and $CPPFLAGS
           construction variables are included on this command line.

       CXXCOMSTR
           The string displayed when a C++ source file is compiled to a
           (static) object file. If this is not set, then $CXXCOM (the command
           line) is displayed.

               env = Environment(CXXCOMSTR = "Compiling static object $TARGET")

       CXXFILESUFFIX
           The suffix for C++ source files. This is used by the internal
           CXXFile builder when generating C++ files from Lex (.ll) or YACC
           (.yy) input files. The default suffix is .cc. SCons also treats
           files with the suffixes .cpp, .cxx, .c++, and .C++ as C++ files,
           and files with .mm suffixes as Objective C++ files. On
           case-sensitive systems (Linux, UNIX, and other POSIX-alikes), SCons
           also treats .C (upper case) files as C++ files.

       CXXFLAGS
           General options that are passed to the C++ compiler. By default,
           this includes the value of $CCFLAGS, so that setting $CCFLAGS
           affects both C and C++ compilation. If you want to add C++-specific
           flags, you must set or override the value of $CXXFLAGS.

       CXXVERSION
           The version number of the C++ compiler. This may or may not be set,
           depending on the specific C++ compiler being used.

       DC
           DC.

       DCOM
           DCOM.

       DDEBUG
           DDEBUG.

       _DDEBUGFLAGS
           _DDEBUGFLAGS.

       DDEBUGPREFIX
           DDEBUGPREFIX.

       DDEBUGSUFFIX
           DDEBUGSUFFIX.

       DESCRIPTION
           A long description of the project being packaged. This is included
           in the relevant section of the file that controls the packaging
           build.

       DESCRIPTION_lang
           A language-specific long description for the specified lang. This
           is used to populate a %description -l section of an RPM .spec file.

       DFILESUFFIX
           DFILESUFFIX.

       DFLAGPREFIX
           DFLAGPREFIX.

       DFLAGS
           DFLAGS.

       _DFLAGS
           _DFLAGS.

       DFLAGSUFFIX
           DFLAGSUFFIX.

       _DINCFLAGS
           _DINCFLAGS.

       DINCPREFIX
           DINCPREFIX.

       DINCSUFFIX
           DINCSUFFIX.

       Dir
           A function that converts a string into a Dir instance relative to
           the target being built.

           A function that converts a string into a Dir instance relative to
           the target being built.

       Dirs
           A function that converts a list of strings into a list of Dir
           instances relative to the target being built.

       DLIB
           DLIB.

       DLIBCOM
           DLIBCOM.

       _DLIBDIRFLAGS
           _DLIBDIRFLAGS.

       DLIBDIRPREFIX
           DLIBDIRPREFIX.

       DLIBDIRSUFFIX
           DLIBDIRSUFFIX.

       DLIBFLAGPREFIX
           DLIBFLAGPREFIX.

       _DLIBFLAGS
           _DLIBFLAGS.

       DLIBFLAGSUFFIX
           DLIBFLAGSUFFIX.

       DLIBLINKPREFIX
           DLIBLINKPREFIX.

       DLIBLINKSUFFIX
           DLIBLINKSUFFIX.

       DLINK
           DLINK.

       DLINKCOM
           DLINKCOM.

       DLINKFLAGPREFIX
           DLINKFLAGPREFIX.

       DLINKFLAGS
           DLINKFLAGS.

       DLINKFLAGSUFFIX
           DLINKFLAGSUFFIX.

       DOCBOOK_DEFAULT_XSL_EPUB
           The default XSLT file for the DocbookEpub builder within the
           current environment, if no other XSLT gets specified via keyword.

       DOCBOOK_DEFAULT_XSL_HTML
           The default XSLT file for the DocbookHtml builder within the
           current environment, if no other XSLT gets specified via keyword.

       DOCBOOK_DEFAULT_XSL_HTMLCHUNKED
           The default XSLT file for the DocbookHtmlChunked builder within the
           current environment, if no other XSLT gets specified via keyword.

       DOCBOOK_DEFAULT_XSL_HTMLHELP
           The default XSLT file for the DocbookHtmlhelp builder within the
           current environment, if no other XSLT gets specified via keyword.

       DOCBOOK_DEFAULT_XSL_MAN
           The default XSLT file for the DocbookMan builder within the current
           environment, if no other XSLT gets specified via keyword.

       DOCBOOK_DEFAULT_XSL_PDF
           The default XSLT file for the DocbookPdf builder within the current
           environment, if no other XSLT gets specified via keyword.

       DOCBOOK_DEFAULT_XSL_SLIDESHTML
           The default XSLT file for the DocbookSlidesHtml builder within the
           current environment, if no other XSLT gets specified via keyword.

       DOCBOOK_DEFAULT_XSL_SLIDESPDF
           The default XSLT file for the DocbookSlidesPdf builder within the
           current environment, if no other XSLT gets specified via keyword.

       DOCBOOK_FOP
           The path to the PDF renderer fop or xep, if one of them is
           installed (fop gets checked first).

       DOCBOOK_FOPCOM
           The full command-line for the PDF renderer fop or xep.

       DOCBOOK_FOPCOMSTR
           The string displayed when a renderer like fop or xep is used to
           create PDF output from an XML file.

       DOCBOOK_FOPFLAGS
           Additonal command-line flags for the PDF renderer fop or xep.

       DOCBOOK_XMLLINT
           The path to the external executable xmllint, if it's installed.
           Note, that this is only used as last fallback for resolving
           XIncludes, if no libxml2 or lxml Python binding can be imported in
           the current system.

       DOCBOOK_XMLLINTCOM
           The full command-line for the external executable xmllint.

       DOCBOOK_XMLLINTCOMSTR
           The string displayed when xmllint is used to resolve XIncludes for
           a given XML file.

       DOCBOOK_XMLLINTFLAGS
           Additonal command-line flags for the external executable xmllint.

       DOCBOOK_XSLTPROC
           The path to the external executable xsltproc (or saxon, xalan), if
           one of them is installed. Note, that this is only used as last
           fallback for XSL transformations, if no libxml2 or lxml Python
           binding can be imported in the current system.

       DOCBOOK_XSLTPROCCOM
           The full command-line for the external executable xsltproc (or
           saxon, xalan).

       DOCBOOK_XSLTPROCCOMSTR
           The string displayed when xsltproc is used to transform an XML file
           via a given XSLT stylesheet.

       DOCBOOK_XSLTPROCFLAGS
           Additonal command-line flags for the external executable xsltproc
           (or saxon, xalan).

       DOCBOOK_XSLTPROCPARAMS
           Additonal parameters that are not intended for the XSLT processor
           executable, but the XSL processing itself. By default, they get
           appended at the end of the command line for saxon and saxon-xslt,
           respectively.

       DPATH
           DPATH.

       DSUFFIXES
           The list of suffixes of files that will be scanned for imported D
           package files. The default list is:

               ['.d']

       _DVERFLAGS
           _DVERFLAGS.

       DVERPREFIX
           DVERPREFIX.

       DVERSIONS
           DVERSIONS.

       DVERSUFFIX
           DVERSUFFIX.

       DVIPDF
           The TeX DVI file to PDF file converter.

       DVIPDFCOM
           The command line used to convert TeX DVI files into a PDF file.

       DVIPDFCOMSTR
           The string displayed when a TeX DVI file is converted into a PDF
           file. If this is not set, then $DVIPDFCOM (the command line) is
           displayed.

       DVIPDFFLAGS
           General options passed to the TeX DVI file to PDF file converter.

       DVIPS
           The TeX DVI file to PostScript converter.

       DVIPSFLAGS
           General options passed to the TeX DVI file to PostScript converter.

       ENV
           A dictionary of environment variables to use when invoking
           commands. When $ENV is used in a command all list values will be
           joined using the path separator and any other non-string values
           will simply be coerced to a string. Note that, by default, scons
           does not propagate the environment in force when you execute scons
           to the commands used to build target files. This is so that builds
           will be guaranteed repeatable regardless of the environment
           variables set at the time scons is invoked.

           If you want to propagate your environment variables to the commands
           executed to build target files, you must do so explicitly:

               import os
               env = Environment(ENV = os.environ)

           Note that you can choose only to propagate certain environment
           variables. A common example is the system PATH environment
           variable, so that scons uses the same utilities as the invoking
           shell (or other process):

               import os
               env = Environment(ENV = {'PATH' : os.environ['PATH']})

       ESCAPE
           A function that will be called to escape shell special characters
           in command lines. The function should take one argument: the
           command line string to escape; and should return the escaped
           command line.

       F03
           The Fortran 03 compiler. You should normally set the $FORTRAN
           variable, which specifies the default Fortran compiler for all
           Fortran versions. You only need to set $F03 if you need to use a
           specific compiler or compiler version for Fortran 03 files.

       F03COM
           The command line used to compile a Fortran 03 source file to an
           object file. You only need to set $F03COM if you need to use a
           specific command line for Fortran 03 files. You should normally set
           the $FORTRANCOM variable, which specifies the default command line
           for all Fortran versions.

       F03COMSTR
           The string displayed when a Fortran 03 source file is compiled to
           an object file. If this is not set, then $F03COM or $FORTRANCOM
           (the command line) is displayed.

       F03FILESUFFIXES
           The list of file extensions for which the F03 dialect will be used.
           By default, this is ['.f03']

       F03FLAGS
           General user-specified options that are passed to the Fortran 03
           compiler. Note that this variable does not contain -I (or similar)
           include search path options that scons generates automatically from
           $F03PATH. See $_F03INCFLAGS below, for the variable that expands to
           those options. You only need to set $F03FLAGS if you need to define
           specific user options for Fortran 03 files. You should normally set
           the $FORTRANFLAGS variable, which specifies the user-specified
           options passed to the default Fortran compiler for all Fortran
           versions.

       _F03INCFLAGS
           An automatically-generated construction variable containing the
           Fortran 03 compiler command-line options for specifying directories
           to be searched for include files. The value of $_F03INCFLAGS is
           created by appending $INCPREFIX and $INCSUFFIX to the beginning and
           end of each directory in $F03PATH.

       F03PATH
           The list of directories that the Fortran 03 compiler will search
           for include directories. The implicit dependency scanner will
           search these directories for include files. Don't explicitly put
           include directory arguments in $F03FLAGS because the result will be
           non-portable and the directories will not be searched by the
           dependency scanner. Note: directory names in $F03PATH will be
           looked-up relative to the SConscript directory when they are used
           in a command. To force scons to look-up a directory relative to the
           root of the source tree use #: You only need to set $F03PATH if you
           need to define a specific include path for Fortran 03 files. You
           should normally set the $FORTRANPATH variable, which specifies the
           include path for the default Fortran compiler for all Fortran
           versions.

               env = Environment(F03PATH='#/include')

           The directory look-up can also be forced using the Dir() function:

               include = Dir('include')
               env = Environment(F03PATH=include)

           The directory list will be added to command lines through the
           automatically-generated $_F03INCFLAGS construction variable, which
           is constructed by appending the values of the $INCPREFIX and
           $INCSUFFIX construction variables to the beginning and end of each
           directory in $F03PATH. Any command lines you define that need the
           F03PATH directory list should include $_F03INCFLAGS:

               env = Environment(F03COM="my_compiler $_F03INCFLAGS -c -o $TARGET $SOURCE")

       F03PPCOM
           The command line used to compile a Fortran 03 source file to an
           object file after first running the file through the C
           preprocessor. Any options specified in the $F03FLAGS and $CPPFLAGS
           construction variables are included on this command line. You only
           need to set $F03PPCOM if you need to use a specific C-preprocessor
           command line for Fortran 03 files. You should normally set the
           $FORTRANPPCOM variable, which specifies the default C-preprocessor
           command line for all Fortran versions.

       F03PPCOMSTR
           The string displayed when a Fortran 03 source file is compiled to
           an object file after first running the file through the C
           preprocessor. If this is not set, then $F03PPCOM or $FORTRANPPCOM
           (the command line) is displayed.

       F03PPFILESUFFIXES
           The list of file extensions for which the compilation +
           preprocessor pass for F03 dialect will be used. By default, this is
           empty

       F08
           The Fortran 08 compiler. You should normally set the $FORTRAN
           variable, which specifies the default Fortran compiler for all
           Fortran versions. You only need to set $F08 if you need to use a
           specific compiler or compiler version for Fortran 08 files.

       F08COM
           The command line used to compile a Fortran 08 source file to an
           object file. You only need to set $F08COM if you need to use a
           specific command line for Fortran 08 files. You should normally set
           the $FORTRANCOM variable, which specifies the default command line
           for all Fortran versions.

       F08COMSTR
           The string displayed when a Fortran 08 source file is compiled to
           an object file. If this is not set, then $F08COM or $FORTRANCOM
           (the command line) is displayed.

       F08FILESUFFIXES
           The list of file extensions for which the F08 dialect will be used.
           By default, this is ['.f08']

       F08FLAGS
           General user-specified options that are passed to the Fortran 08
           compiler. Note that this variable does not contain -I (or similar)
           include search path options that scons generates automatically from
           $F08PATH. See $_F08INCFLAGS below, for the variable that expands to
           those options. You only need to set $F08FLAGS if you need to define
           specific user options for Fortran 08 files. You should normally set
           the $FORTRANFLAGS variable, which specifies the user-specified
           options passed to the default Fortran compiler for all Fortran
           versions.

       _F08INCFLAGS
           An automatically-generated construction variable containing the
           Fortran 08 compiler command-line options for specifying directories
           to be searched for include files. The value of $_F08INCFLAGS is
           created by appending $INCPREFIX and $INCSUFFIX to the beginning and
           end of each directory in $F08PATH.

       F08PATH
           The list of directories that the Fortran 08 compiler will search
           for include directories. The implicit dependency scanner will
           search these directories for include files. Don't explicitly put
           include directory arguments in $F08FLAGS because the result will be
           non-portable and the directories will not be searched by the
           dependency scanner. Note: directory names in $F08PATH will be
           looked-up relative to the SConscript directory when they are used
           in a command. To force scons to look-up a directory relative to the
           root of the source tree use #: You only need to set $F08PATH if you
           need to define a specific include path for Fortran 08 files. You
           should normally set the $FORTRANPATH variable, which specifies the
           include path for the default Fortran compiler for all Fortran
           versions.

               env = Environment(F08PATH='#/include')

           The directory look-up can also be forced using the Dir() function:

               include = Dir('include')
               env = Environment(F08PATH=include)

           The directory list will be added to command lines through the
           automatically-generated $_F08INCFLAGS construction variable, which
           is constructed by appending the values of the $INCPREFIX and
           $INCSUFFIX construction variables to the beginning and end of each
           directory in $F08PATH. Any command lines you define that need the
           F08PATH directory list should include $_F08INCFLAGS:

               env = Environment(F08COM="my_compiler $_F08INCFLAGS -c -o $TARGET $SOURCE")

       F08PPCOM
           The command line used to compile a Fortran 08 source file to an
           object file after first running the file through the C
           preprocessor. Any options specified in the $F08FLAGS and $CPPFLAGS
           construction variables are included on this command line. You only
           need to set $F08PPCOM if you need to use a specific C-preprocessor
           command line for Fortran 08 files. You should normally set the
           $FORTRANPPCOM variable, which specifies the default C-preprocessor
           command line for all Fortran versions.

       F08PPCOMSTR
           The string displayed when a Fortran 08 source file is compiled to
           an object file after first running the file through the C
           preprocessor. If this is not set, then $F08PPCOM or $FORTRANPPCOM
           (the command line) is displayed.

       F08PPFILESUFFIXES
           The list of file extensions for which the compilation +
           preprocessor pass for F08 dialect will be used. By default, this is
           empty

       F77
           The Fortran 77 compiler. You should normally set the $FORTRAN
           variable, which specifies the default Fortran compiler for all
           Fortran versions. You only need to set $F77 if you need to use a
           specific compiler or compiler version for Fortran 77 files.

       F77COM
           The command line used to compile a Fortran 77 source file to an
           object file. You only need to set $F77COM if you need to use a
           specific command line for Fortran 77 files. You should normally set
           the $FORTRANCOM variable, which specifies the default command line
           for all Fortran versions.

       F77COMSTR
           The string displayed when a Fortran 77 source file is compiled to
           an object file. If this is not set, then $F77COM or $FORTRANCOM
           (the command line) is displayed.

       F77FILESUFFIXES
           The list of file extensions for which the F77 dialect will be used.
           By default, this is ['.f77']

       F77FLAGS
           General user-specified options that are passed to the Fortran 77
           compiler. Note that this variable does not contain -I (or similar)
           include search path options that scons generates automatically from
           $F77PATH. See $_F77INCFLAGS below, for the variable that expands to
           those options. You only need to set $F77FLAGS if you need to define
           specific user options for Fortran 77 files. You should normally set
           the $FORTRANFLAGS variable, which specifies the user-specified
           options passed to the default Fortran compiler for all Fortran
           versions.

       _F77INCFLAGS
           An automatically-generated construction variable containing the
           Fortran 77 compiler command-line options for specifying directories
           to be searched for include files. The value of $_F77INCFLAGS is
           created by appending $INCPREFIX and $INCSUFFIX to the beginning and
           end of each directory in $F77PATH.

       F77PATH
           The list of directories that the Fortran 77 compiler will search
           for include directories. The implicit dependency scanner will
           search these directories for include files. Don't explicitly put
           include directory arguments in $F77FLAGS because the result will be
           non-portable and the directories will not be searched by the
           dependency scanner. Note: directory names in $F77PATH will be
           looked-up relative to the SConscript directory when they are used
           in a command. To force scons to look-up a directory relative to the
           root of the source tree use #: You only need to set $F77PATH if you
           need to define a specific include path for Fortran 77 files. You
           should normally set the $FORTRANPATH variable, which specifies the
           include path for the default Fortran compiler for all Fortran
           versions.

               env = Environment(F77PATH='#/include')

           The directory look-up can also be forced using the Dir() function:

               include = Dir('include')
               env = Environment(F77PATH=include)

           The directory list will be added to command lines through the
           automatically-generated $_F77INCFLAGS construction variable, which
           is constructed by appending the values of the $INCPREFIX and
           $INCSUFFIX construction variables to the beginning and end of each
           directory in $F77PATH. Any command lines you define that need the
           F77PATH directory list should include $_F77INCFLAGS:

               env = Environment(F77COM="my_compiler $_F77INCFLAGS -c -o $TARGET $SOURCE")

       F77PPCOM
           The command line used to compile a Fortran 77 source file to an
           object file after first running the file through the C
           preprocessor. Any options specified in the $F77FLAGS and $CPPFLAGS
           construction variables are included on this command line. You only
           need to set $F77PPCOM if you need to use a specific C-preprocessor
           command line for Fortran 77 files. You should normally set the
           $FORTRANPPCOM variable, which specifies the default C-preprocessor
           command line for all Fortran versions.

       F77PPCOMSTR
           The string displayed when a Fortran 77 source file is compiled to
           an object file after first running the file through the C
           preprocessor. If this is not set, then $F77PPCOM or $FORTRANPPCOM
           (the command line) is displayed.

       F77PPFILESUFFIXES
           The list of file extensions for which the compilation +
           preprocessor pass for F77 dialect will be used. By default, this is
           empty

       F90
           The Fortran 90 compiler. You should normally set the $FORTRAN
           variable, which specifies the default Fortran compiler for all
           Fortran versions. You only need to set $F90 if you need to use a
           specific compiler or compiler version for Fortran 90 files.

       F90COM
           The command line used to compile a Fortran 90 source file to an
           object file. You only need to set $F90COM if you need to use a
           specific command line for Fortran 90 files. You should normally set
           the $FORTRANCOM variable, which specifies the default command line
           for all Fortran versions.

       F90COMSTR
           The string displayed when a Fortran 90 source file is compiled to
           an object file. If this is not set, then $F90COM or $FORTRANCOM
           (the command line) is displayed.

       F90FILESUFFIXES
           The list of file extensions for which the F90 dialect will be used.
           By default, this is ['.f90']

       F90FLAGS
           General user-specified options that are passed to the Fortran 90
           compiler. Note that this variable does not contain -I (or similar)
           include search path options that scons generates automatically from
           $F90PATH. See $_F90INCFLAGS below, for the variable that expands to
           those options. You only need to set $F90FLAGS if you need to define
           specific user options for Fortran 90 files. You should normally set
           the $FORTRANFLAGS variable, which specifies the user-specified
           options passed to the default Fortran compiler for all Fortran
           versions.

       _F90INCFLAGS
           An automatically-generated construction variable containing the
           Fortran 90 compiler command-line options for specifying directories
           to be searched for include files. The value of $_F90INCFLAGS is
           created by appending $INCPREFIX and $INCSUFFIX to the beginning and
           end of each directory in $F90PATH.

       F90PATH
           The list of directories that the Fortran 90 compiler will search
           for include directories. The implicit dependency scanner will
           search these directories for include files. Don't explicitly put
           include directory arguments in $F90FLAGS because the result will be
           non-portable and the directories will not be searched by the
           dependency scanner. Note: directory names in $F90PATH will be
           looked-up relative to the SConscript directory when they are used
           in a command. To force scons to look-up a directory relative to the
           root of the source tree use #: You only need to set $F90PATH if you
           need to define a specific include path for Fortran 90 files. You
           should normally set the $FORTRANPATH variable, which specifies the
           include path for the default Fortran compiler for all Fortran
           versions.

               env = Environment(F90PATH='#/include')

           The directory look-up can also be forced using the Dir() function:

               include = Dir('include')
               env = Environment(F90PATH=include)

           The directory list will be added to command lines through the
           automatically-generated $_F90INCFLAGS construction variable, which
           is constructed by appending the values of the $INCPREFIX and
           $INCSUFFIX construction variables to the beginning and end of each
           directory in $F90PATH. Any command lines you define that need the
           F90PATH directory list should include $_F90INCFLAGS:

               env = Environment(F90COM="my_compiler $_F90INCFLAGS -c -o $TARGET $SOURCE")

       F90PPCOM
           The command line used to compile a Fortran 90 source file to an
           object file after first running the file through the C
           preprocessor. Any options specified in the $F90FLAGS and $CPPFLAGS
           construction variables are included on this command line. You only
           need to set $F90PPCOM if you need to use a specific C-preprocessor
           command line for Fortran 90 files. You should normally set the
           $FORTRANPPCOM variable, which specifies the default C-preprocessor
           command line for all Fortran versions.

       F90PPCOMSTR
           The string displayed when a Fortran 90 source file is compiled
           after first running the file through the C preprocessor. If this is
           not set, then $F90PPCOM or $FORTRANPPCOM (the command line) is
           displayed.

       F90PPFILESUFFIXES
           The list of file extensions for which the compilation +
           preprocessor pass for F90 dialect will be used. By default, this is
           empty

       F95
           The Fortran 95 compiler. You should normally set the $FORTRAN
           variable, which specifies the default Fortran compiler for all
           Fortran versions. You only need to set $F95 if you need to use a
           specific compiler or compiler version for Fortran 95 files.

       F95COM
           The command line used to compile a Fortran 95 source file to an
           object file. You only need to set $F95COM if you need to use a
           specific command line for Fortran 95 files. You should normally set
           the $FORTRANCOM variable, which specifies the default command line
           for all Fortran versions.

       F95COMSTR
           The string displayed when a Fortran 95 source file is compiled to
           an object file. If this is not set, then $F95COM or $FORTRANCOM
           (the command line) is displayed.

       F95FILESUFFIXES
           The list of file extensions for which the F95 dialect will be used.
           By default, this is ['.f95']

       F95FLAGS
           General user-specified options that are passed to the Fortran 95
           compiler. Note that this variable does not contain -I (or similar)
           include search path options that scons generates automatically from
           $F95PATH. See $_F95INCFLAGS below, for the variable that expands to
           those options. You only need to set $F95FLAGS if you need to define
           specific user options for Fortran 95 files. You should normally set
           the $FORTRANFLAGS variable, which specifies the user-specified
           options passed to the default Fortran compiler for all Fortran
           versions.

       _F95INCFLAGS
           An automatically-generated construction variable containing the
           Fortran 95 compiler command-line options for specifying directories
           to be searched for include files. The value of $_F95INCFLAGS is
           created by appending $INCPREFIX and $INCSUFFIX to the beginning and
           end of each directory in $F95PATH.

       F95PATH
           The list of directories that the Fortran 95 compiler will search
           for include directories. The implicit dependency scanner will
           search these directories for include files. Don't explicitly put
           include directory arguments in $F95FLAGS because the result will be
           non-portable and the directories will not be searched by the
           dependency scanner. Note: directory names in $F95PATH will be
           looked-up relative to the SConscript directory when they are used
           in a command. To force scons to look-up a directory relative to the
           root of the source tree use #: You only need to set $F95PATH if you
           need to define a specific include path for Fortran 95 files. You
           should normally set the $FORTRANPATH variable, which specifies the
           include path for the default Fortran compiler for all Fortran
           versions.

               env = Environment(F95PATH='#/include')

           The directory look-up can also be forced using the Dir() function:

               include = Dir('include')
               env = Environment(F95PATH=include)

           The directory list will be added to command lines through the
           automatically-generated $_F95INCFLAGS construction variable, which
           is constructed by appending the values of the $INCPREFIX and
           $INCSUFFIX construction variables to the beginning and end of each
           directory in $F95PATH. Any command lines you define that need the
           F95PATH directory list should include $_F95INCFLAGS:

               env = Environment(F95COM="my_compiler $_F95INCFLAGS -c -o $TARGET $SOURCE")

       F95PPCOM
           The command line used to compile a Fortran 95 source file to an
           object file after first running the file through the C
           preprocessor. Any options specified in the $F95FLAGS and $CPPFLAGS
           construction variables are included on this command line. You only
           need to set $F95PPCOM if you need to use a specific C-preprocessor
           command line for Fortran 95 files. You should normally set the
           $FORTRANPPCOM variable, which specifies the default C-preprocessor
           command line for all Fortran versions.

       F95PPCOMSTR
           The string displayed when a Fortran 95 source file is compiled to
           an object file after first running the file through the C
           preprocessor. If this is not set, then $F95PPCOM or $FORTRANPPCOM
           (the command line) is displayed.

       F95PPFILESUFFIXES
           The list of file extensions for which the compilation +
           preprocessor pass for F95 dialect will be used. By default, this is
           empty

       File
           A function that converts a string into a File instance relative to
           the target being built.

           A function that converts a string into a File instance relative to
           the target being built.

       FORTRAN
           The default Fortran compiler for all versions of Fortran.

       FORTRANCOM
           The command line used to compile a Fortran source file to an object
           file. By default, any options specified in the $FORTRANFLAGS,
           $CPPFLAGS, $_CPPDEFFLAGS, $_FORTRANMODFLAG, and $_FORTRANINCFLAGS
           construction variables are included on this command line.

       FORTRANCOMSTR
           The string displayed when a Fortran source file is compiled to an
           object file. If this is not set, then $FORTRANCOM (the command
           line) is displayed.

       FORTRANFILESUFFIXES
           The list of file extensions for which the FORTRAN dialect will be
           used. By default, this is ['.f', '.for', '.ftn']

       FORTRANFLAGS
           General user-specified options that are passed to the Fortran
           compiler. Note that this variable does not contain -I (or similar)
           include or module search path options that scons generates
           automatically from $FORTRANPATH. See $_FORTRANINCFLAGS and
           $_FORTRANMODFLAG, below, for the variables that expand those
           options.

       _FORTRANINCFLAGS
           An automatically-generated construction variable containing the
           Fortran compiler command-line options for specifying directories to
           be searched for include files and module files. The value of
           $_FORTRANINCFLAGS is created by prepending/appending $INCPREFIX and
           $INCSUFFIX to the beginning and end of each directory in
           $FORTRANPATH.

       FORTRANMODDIR
           Directory location where the Fortran compiler should place any
           module files it generates. This variable is empty, by default. Some
           Fortran compilers will internally append this directory in the
           search path for module files, as well.

       FORTRANMODDIRPREFIX
           The prefix used to specify a module directory on the Fortran
           compiler command line. This will be appended to the beginning of
           the directory in the $FORTRANMODDIR construction variables when the
           $_FORTRANMODFLAG variables is automatically generated.

       FORTRANMODDIRSUFFIX
           The suffix used to specify a module directory on the Fortran
           compiler command line. This will be appended to the beginning of
           the directory in the $FORTRANMODDIR construction variables when the
           $_FORTRANMODFLAG variables is automatically generated.

       _FORTRANMODFLAG
           An automatically-generated construction variable containing the
           Fortran compiler command-line option for specifying the directory
           location where the Fortran compiler should place any module files
           that happen to get generated during compilation. The value of
           $_FORTRANMODFLAG is created by prepending/appending
           $FORTRANMODDIRPREFIX and $FORTRANMODDIRSUFFIX to the beginning and
           end of the directory in $FORTRANMODDIR.

       FORTRANMODPREFIX
           The module file prefix used by the Fortran compiler. SCons assumes
           that the Fortran compiler follows the quasi-standard naming
           convention for module files of module_name.mod. As a result, this
           variable is left empty, by default. For situations in which the
           compiler does not necessarily follow the normal convention, the
           user may use this variable. Its value will be appended to every
           module file name as scons attempts to resolve dependencies.

       FORTRANMODSUFFIX
           The module file suffix used by the Fortran compiler. SCons assumes
           that the Fortran compiler follows the quasi-standard naming
           convention for module files of module_name.mod. As a result, this
           variable is set to ".mod", by default. For situations in which the
           compiler does not necessarily follow the normal convention, the
           user may use this variable. Its value will be appended to every
           module file name as scons attempts to resolve dependencies.

       FORTRANPATH
           The list of directories that the Fortran compiler will search for
           include files and (for some compilers) module files. The Fortran
           implicit dependency scanner will search these directories for
           include files (but not module files since they are autogenerated
           and, as such, may not actually exist at the time the scan takes
           place). Don't explicitly put include directory arguments in
           FORTRANFLAGS because the result will be non-portable and the
           directories will not be searched by the dependency scanner. Note:
           directory names in FORTRANPATH will be looked-up relative to the
           SConscript directory when they are used in a command. To force
           scons to look-up a directory relative to the root of the source
           tree use #:

               env = Environment(FORTRANPATH='#/include')

           The directory look-up can also be forced using the Dir() function:

               include = Dir('include')
               env = Environment(FORTRANPATH=include)

           The directory list will be added to command lines through the
           automatically-generated $_FORTRANINCFLAGS construction variable,
           which is constructed by appending the values of the $INCPREFIX and
           $INCSUFFIX construction variables to the beginning and end of each
           directory in $FORTRANPATH. Any command lines you define that need
           the FORTRANPATH directory list should include $_FORTRANINCFLAGS:

               env = Environment(FORTRANCOM="my_compiler $_FORTRANINCFLAGS -c -o $TARGET $SOURCE")

       FORTRANPPCOM
           The command line used to compile a Fortran source file to an object
           file after first running the file through the C preprocessor. By
           default, any options specified in the $FORTRANFLAGS, $CPPFLAGS,
           $_CPPDEFFLAGS, $_FORTRANMODFLAG, and $_FORTRANINCFLAGS construction
           variables are included on this command line.

       FORTRANPPCOMSTR
           The string displayed when a Fortran source file is compiled to an
           object file after first running the file through the C
           preprocessor. If this is not set, then $FORTRANPPCOM (the command
           line) is displayed.

       FORTRANPPFILESUFFIXES
           The list of file extensions for which the compilation +
           preprocessor pass for FORTRAN dialect will be used. By default,
           this is ['.fpp', '.FPP']

       FORTRANSUFFIXES
           The list of suffixes of files that will be scanned for Fortran
           implicit dependencies (INCLUDE lines and USE statements). The
           default list is:

               [".f", ".F", ".for", ".FOR", ".ftn", ".FTN", ".fpp", ".FPP",
               ".f77", ".F77", ".f90", ".F90", ".f95", ".F95"]

       FRAMEWORKPATH
           On Mac OS X with gcc, a list containing the paths to search for
           frameworks. Used by the compiler to find framework-style includes
           like #include <Fmwk/Header.h>. Used by the linker to find
           user-specified frameworks when linking (see $FRAMEWORKS). For
           example:

                env.AppendUnique(FRAMEWORKPATH='#myframeworkdir')

           will add

                 ... -Fmyframeworkdir

           to the compiler and linker command lines.

       _FRAMEWORKPATH
           On Mac OS X with gcc, an automatically-generated construction
           variable containing the linker command-line options corresponding
           to $FRAMEWORKPATH.

       FRAMEWORKPATHPREFIX
           On Mac OS X with gcc, the prefix to be used for the FRAMEWORKPATH
           entries. (see $FRAMEWORKPATH). The default value is -F.

       FRAMEWORKPREFIX
           On Mac OS X with gcc, the prefix to be used for linking in
           frameworks (see $FRAMEWORKS). The default value is -framework.

       _FRAMEWORKS
           On Mac OS X with gcc, an automatically-generated construction
           variable containing the linker command-line options for linking
           with FRAMEWORKS.

       FRAMEWORKS
           On Mac OS X with gcc, a list of the framework names to be linked
           into a program or shared library or bundle. The default value is
           the empty list. For example:

                env.AppendUnique(FRAMEWORKS=Split('System Cocoa SystemConfiguration'))

       FRAMEWORKSFLAGS
           On Mac OS X with gcc, general user-supplied frameworks options to
           be added at the end of a command line building a loadable module.
           (This has been largely superseded by the $FRAMEWORKPATH,
           $FRAMEWORKPATHPREFIX, $FRAMEWORKPREFIX and $FRAMEWORKS variables
           described above.)

       GS
           The Ghostscript program used, e.g. to convert PostScript to PDF
           files.

       GSCOM
           The full Ghostscript command line used for the conversion process.
           Its default value is "$GS $GSFLAGS -sOutputFile=$TARGET $SOURCES".

       GSCOMSTR
           The string displayed when Ghostscript is called for the conversion
           process. If this is not set (the default), then $GSCOM (the command
           line) is displayed.

       GSFLAGS
           General options passed to the Ghostscript program, when converting
           PostScript to PDF files for example. Its default value is
           "-dNOPAUSE -dBATCH -sDEVICE=pdfwrite"

       HOST_ARCH
           Sets the host architecture for Visual Studio compiler. If not set,
           default to the detected host architecture: note that this may
           depend on the python you are using. This variable must be passed as
           an argument to the Environment() constructor; setting it later has
           no effect.

           Valid values are the same as for $TARGET_ARCH.

           This is currently only used on Windows, but in the future it will
           be used on other OSes as well.

           The name of the host hardware architecture used to create the
           Environment. If a platform is specified when creating the
           Environment, then that Platform's logic will handle setting this
           value. This value is immutable, and should not be changed by the
           user after the Environment is initialized. Currently only set for
           Win32.

       HOST_OS
           The name of the host operating system used to create the
           Environment. If a platform is specified when creating the
           Environment, then that Platform's logic will handle setting this
           value. This value is immutable, and should not be changed by the
           user after the Environment is initialized. Currently only set for
           Win32.

       IDLSUFFIXES
           The list of suffixes of files that will be scanned for IDL implicit
           dependencies (#include or import lines). The default list is:

               [".idl", ".IDL"]

       IMPLIBNOVERSIONSYMLINKS
           Used to override $SHLIBNOVERSIONSYMLINKS/$LDMODULENOVERSIONSYMLINKS
           when creating versioned import library for a shared
           library/loadable module. If not defined, then
           $SHLIBNOVERSIONSYMLINKS/$LDMODULENOVERSIONSYMLINKS is used to
           determine whether to disable symlink generation or not.

       IMPLIBPREFIX
           The prefix used for import library names. For example, cygwin uses
           import libraries (libfoo.dll.a) in pair with dynamic libraries
           (cygfoo.dll). The cyglink linker sets $IMPLIBPREFIX to 'lib' and
           $SHLIBPREFIX to 'cyg'.

       IMPLIBSUFFIX
           The suffix used for import library names. For example, cygwin uses
           import libraries (libfoo.dll.a) in pair with dynamic libraries
           (cygfoo.dll). The cyglink linker sets $IMPLIBSUFFIX to '.dll.a' and
           $SHLIBSUFFIX to '.dll'.

       IMPLIBVERSION
           Used to override $SHLIBVERSION/$LDMODULEVERSION when generating
           versioned import library for a shared library/loadable module. If
           undefined, the $SHLIBVERSION/$LDMODULEVERSION is used to determine
           the version of versioned import library.

       IMPLICIT_COMMAND_DEPENDENCIES
           Controls whether or not SCons will add implicit dependencies for
           the commands executed to build targets.

           By default, SCons will add to each target an implicit dependency on
           the command represented by the first argument on any command line
           it executes. The specific file for the dependency is found by
           searching the PATH variable in the ENV environment used to execute
           the command.

           If the construction variable $IMPLICIT_COMMAND_DEPENDENCIES is set
           to a false value (None, False, 0, etc.), then the implicit
           dependency will not be added to the targets built with that
           construction environment.

               env = Environment(IMPLICIT_COMMAND_DEPENDENCIES = 0)

       INCPREFIX
           The prefix used to specify an include directory on the C compiler
           command line. This will be appended to the beginning of each
           directory in the $CPPPATH and $FORTRANPATH construction variables
           when the $_CPPINCFLAGS and $_FORTRANINCFLAGS variables are
           automatically generated.

       INCSUFFIX
           The suffix used to specify an include directory on the C compiler
           command line. This will be appended to the end of each directory in
           the $CPPPATH and $FORTRANPATH construction variables when the
           $_CPPINCFLAGS and $_FORTRANINCFLAGS variables are automatically
           generated.

       INSTALL
           A function to be called to install a file into a destination file
           name. The default function copies the file into the destination
           (and sets the destination file's mode and permission bits to match
           the source file's). The function takes the following arguments:

               def install(dest, source, env):


           dest is the path name of the destination file.  source is the path
           name of the source file.  env is the construction environment (a
           dictionary of construction values) in force for this file
           installation.

       INSTALLSTR
           The string displayed when a file is installed into a destination
           file name. The default is:

               Install file: "$SOURCE" as "$TARGET"

       INTEL_C_COMPILER_VERSION
           Set by the "intelc" Tool to the major version number of the Intel C
           compiler selected for use.

       JAR
           The Java archive tool.

           The Java archive tool.

       JARCHDIR
           The directory to which the Java archive tool should change (using
           the -C option).

           The directory to which the Java archive tool should change (using
           the -C option).

       JARCOM
           The command line used to call the Java archive tool.

           The command line used to call the Java archive tool.

       JARCOMSTR
           The string displayed when the Java archive tool is called If this
           is not set, then $JARCOM (the command line) is displayed.

               env = Environment(JARCOMSTR = "JARchiving $SOURCES into $TARGET")

           The string displayed when the Java archive tool is called If this
           is not set, then $JARCOM (the command line) is displayed.

               env = Environment(JARCOMSTR = "JARchiving $SOURCES into $TARGET")

       JARFLAGS
           General options passed to the Java archive tool. By default this is
           set to cf to create the necessary jar file.

           General options passed to the Java archive tool. By default this is
           set to cf to create the necessary jar file.

       JARSUFFIX
           The suffix for Java archives: .jar by default.

           The suffix for Java archives: .jar by default.

       JAVABOOTCLASSPATH
           Specifies the list of directories that will be added to the javac
           command line via the -bootclasspath option. The individual
           directory names will be separated by the operating system's path
           separate character (: on UNIX/Linux/POSIX, ; on Windows).

       JAVAC
           The Java compiler.

       JAVACCOM
           The command line used to compile a directory tree containing Java
           source files to corresponding Java class files. Any options
           specified in the $JAVACFLAGS construction variable are included on
           this command line.

       JAVACCOMSTR
           The string displayed when compiling a directory tree of Java source
           files to corresponding Java class files. If this is not set, then
           $JAVACCOM (the command line) is displayed.

               env = Environment(JAVACCOMSTR = "Compiling class files $TARGETS from $SOURCES")

       JAVACFLAGS
           General options that are passed to the Java compiler.

       JAVACLASSDIR
           The directory in which Java class files may be found. This is
           stripped from the beginning of any Java .class file names supplied
           to the JavaH builder.

       JAVACLASSPATH
           Specifies the list of directories that will be searched for Java
           .class file. The directories in this list will be added to the
           javac and javah command lines via the -classpath option. The
           individual directory names will be separated by the operating
           system's path separate character (: on UNIX/Linux/POSIX, ; on
           Windows).

           Note that this currently just adds the specified directory via the
           -classpath option.  SCons does not currently search the
           $JAVACLASSPATH directories for dependency .class files.

       JAVACLASSSUFFIX
           The suffix for Java class files; .class by default.

       JAVAH
           The Java generator for C header and stub files.

       JAVAHCOM
           The command line used to generate C header and stub files from Java
           classes. Any options specified in the $JAVAHFLAGS construction
           variable are included on this command line.

       JAVAHCOMSTR
           The string displayed when C header and stub files are generated
           from Java classes. If this is not set, then $JAVAHCOM (the command
           line) is displayed.

               env = Environment(JAVAHCOMSTR = "Generating header/stub file(s) $TARGETS from $SOURCES")

       JAVAHFLAGS
           General options passed to the C header and stub file generator for
           Java classes.

       JAVASOURCEPATH
           Specifies the list of directories that will be searched for input
           .java file. The directories in this list will be added to the javac
           command line via the -sourcepath option. The individual directory
           names will be separated by the operating system's path separate
           character (: on UNIX/Linux/POSIX, ; on Windows).

           Note that this currently just adds the specified directory via the
           -sourcepath option.  SCons does not currently search the
           $JAVASOURCEPATH directories for dependency .java files.

       JAVASUFFIX
           The suffix for Java files; .java by default.

       JAVAVERSION
           Specifies the Java version being used by the Java builder. This is
           not currently used to select one version of the Java compiler vs.
           another. Instead, you should set this to specify the version of
           Java supported by your javac compiler. The default is 1.4.

           This is sometimes necessary because Java 1.5 changed the file names
           that are created for nested anonymous inner classes, which can
           cause a mismatch with the files that SCons expects will be
           generated by the javac compiler. Setting $JAVAVERSION to 1.5 (or
           1.6, as appropriate) can make SCons realize that a Java 1.5 or 1.6
           build is actually up to date.

       LATEX
           The LaTeX structured formatter and typesetter.

       LATEXCOM
           The command line used to call the LaTeX structured formatter and
           typesetter.

       LATEXCOMSTR
           The string displayed when calling the LaTeX structured formatter
           and typesetter. If this is not set, then $LATEXCOM (the command
           line) is displayed.

               env = Environment(LATEXCOMSTR = "Building $TARGET from LaTeX input $SOURCES")

       LATEXFLAGS
           General options passed to the LaTeX structured formatter and
           typesetter.

       LATEXRETRIES
           The maximum number of times that LaTeX will be re-run if the .log
           generated by the $LATEXCOM command indicates that there are
           undefined references. The default is to try to resolve undefined
           references by re-running LaTeX up to three times.

       LATEXSUFFIXES
           The list of suffixes of files that will be scanned for LaTeX
           implicit dependencies (\include or \import files). The default list
           is:

               [".tex", ".ltx", ".latex"]

       LDMODULE
           The linker for building loadable modules. By default, this is the
           same as $SHLINK.

       LDMODULECOM
           The command line for building loadable modules. On Mac OS X, this
           uses the $LDMODULE, $LDMODULEFLAGS and $FRAMEWORKSFLAGS variables.
           On other systems, this is the same as $SHLINK.

       LDMODULECOMSTR
           The string displayed when building loadable modules. If this is not
           set, then $LDMODULECOM (the command line) is displayed.

       LDMODULEFLAGS
           General user options passed to the linker for building loadable
           modules.

       LDMODULENOVERSIONSYMLINKS
           Instructs the LoadableModule builder to not automatically create
           symlinks for versioned modules. Defaults to $SHLIBNOVERSIONSYMLINKS

       LDMODULEPREFIX
           The prefix used for loadable module file names. On Mac OS X, this
           is null; on other systems, this is the same as $SHLIBPREFIX.

       _LDMODULESONAME
           A macro that automatically generates loadable module's SONAME based
           on $TARGET, $LDMODULEVERSION and $LDMODULESUFFIX. Used by
           LoadableModule builder when the linker tool supports SONAME (e.g.
           gnulink).

       LDMODULESUFFIX
           The suffix used for loadable module file names. On Mac OS X, this
           is null; on other systems, this is the same as $SHLIBSUFFIX.

       LDMODULEVERSION
           When this construction variable is defined, a versioned loadable
           module is created by LoadableModule builder. This activates the
           $_LDMODULEVERSIONFLAGS and thus modifies the $LDMODULECOM as
           required, adds the version number to the library name, and creates
           the symlinks that are needed.  $LDMODULEVERSION versions should
           exist in the same format as $SHLIBVERSION.

       LDMODULEVERSIONFLAGS
           Extra flags added to $LDMODULECOM when building versioned
           LoadableModule. These flags are only used when $LDMODULEVERSION is
           set.

       _LDMODULEVERSIONFLAGS
           This macro automatically introduces extra flags to $LDMODULECOM
           when building versioned LoadableModule (that is when
           $LDMODULEVERSION is set).  _LDMODULEVERSIONFLAGS usually adds
           $SHLIBVERSIONFLAGS and some extra dynamically generated options
           (such as -Wl,-soname=$_LDMODULESONAME). It is unused by plain
           (unversioned) loadable modules.

       LEX
           The lexical analyzer generator.

       LEXCOM
           The command line used to call the lexical analyzer generator to
           generate a source file.

       LEXCOMSTR
           The string displayed when generating a source file using the
           lexical analyzer generator. If this is not set, then $LEXCOM (the
           command line) is displayed.

               env = Environment(LEXCOMSTR = "Lex'ing $TARGET from $SOURCES")

       LEXFLAGS
           General options passed to the lexical analyzer generator.

       _LIBDIRFLAGS
           An automatically-generated construction variable containing the
           linker command-line options for specifying directories to be
           searched for library. The value of $_LIBDIRFLAGS is created by
           appending $LIBDIRPREFIX and $LIBDIRSUFFIX to the beginning and end
           of each directory in $LIBPATH.

       LIBDIRPREFIX
           The prefix used to specify a library directory on the linker
           command line. This will be appended to the beginning of each
           directory in the $LIBPATH construction variable when the
           $_LIBDIRFLAGS variable is automatically generated.

       LIBDIRSUFFIX
           The suffix used to specify a library directory on the linker
           command line. This will be appended to the end of each directory in
           the $LIBPATH construction variable when the $_LIBDIRFLAGS variable
           is automatically generated.

       LIBEMITTER
           TODO

       _LIBFLAGS
           An automatically-generated construction variable containing the
           linker command-line options for specifying libraries to be linked
           with the resulting target. The value of $_LIBFLAGS is created by
           appending $LIBLINKPREFIX and $LIBLINKSUFFIX to the beginning and
           end of each filename in $LIBS.

       LIBLINKPREFIX
           The prefix used to specify a library to link on the linker command
           line. This will be appended to the beginning of each library in the
           $LIBS construction variable when the $_LIBFLAGS variable is
           automatically generated.

       LIBLINKSUFFIX
           The suffix used to specify a library to link on the linker command
           line. This will be appended to the end of each library in the $LIBS
           construction variable when the $_LIBFLAGS variable is automatically
           generated.

       LIBPATH
           The list of directories that will be searched for libraries. The
           implicit dependency scanner will search these directories for
           include files. Don't explicitly put include directory arguments in
           $LINKFLAGS or $SHLINKFLAGS because the result will be non-portable
           and the directories will not be searched by the dependency scanner.
           Note: directory names in LIBPATH will be looked-up relative to the
           SConscript directory when they are used in a command. To force
           scons to look-up a directory relative to the root of the source
           tree use #:

               env = Environment(LIBPATH='#/libs')

           The directory look-up can also be forced using the Dir() function:

               libs = Dir('libs')
               env = Environment(LIBPATH=libs)

           The directory list will be added to command lines through the
           automatically-generated $_LIBDIRFLAGS construction variable, which
           is constructed by appending the values of the $LIBDIRPREFIX and
           $LIBDIRSUFFIX construction variables to the beginning and end of
           each directory in $LIBPATH. Any command lines you define that need
           the LIBPATH directory list should include $_LIBDIRFLAGS:

               env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")

       LIBPREFIX
           The prefix used for (static) library file names. A default value is
           set for each platform (posix, win32, os2, etc.), but the value is
           overridden by individual tools (ar, mslib, sgiar, sunar, tlib,
           etc.) to reflect the names of the libraries they create.

       LIBPREFIXES
           A list of all legal prefixes for library file names. When searching
           for library dependencies, SCons will look for files with these
           prefixes, the base library name, and suffixes in the $LIBSUFFIXES
           list.

       LIBS
           A list of one or more libraries that will be linked with any
           executable programs created by this environment.

           The library list will be added to command lines through the
           automatically-generated $_LIBFLAGS construction variable, which is
           constructed by appending the values of the $LIBLINKPREFIX and
           $LIBLINKSUFFIX construction variables to the beginning and end of
           each filename in $LIBS. Any command lines you define that need the
           LIBS library list should include $_LIBFLAGS:

               env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")

           If you add a File object to the $LIBS list, the name of that file
           will be added to $_LIBFLAGS, and thus the link line, as is, without
           $LIBLINKPREFIX or $LIBLINKSUFFIX. For example:

               env.Append(LIBS=File('/tmp/mylib.so'))

           In all cases, scons will add dependencies from the executable
           program to all the libraries in this list.

       LIBSUFFIX
           The suffix used for (static) library file names. A default value is
           set for each platform (posix, win32, os2, etc.), but the value is
           overridden by individual tools (ar, mslib, sgiar, sunar, tlib,
           etc.) to reflect the names of the libraries they create.

       LIBSUFFIXES
           A list of all legal suffixes for library file names. When searching
           for library dependencies, SCons will look for files with prefixes,
           in the $LIBPREFIXES list, the base library name, and these
           suffixes.

       LICENSE
           The abbreviated name of the license under which this project is
           released (gpl, lpgl, bsd etc.). See
           http://www.opensource.org/licenses/alphabetical for a list of
           license names.

       LINESEPARATOR
           The separator used by the Substfile and Textfile builders. This
           value is used between sources when constructing the target. It
           defaults to the current system line separator.

       LINGUAS_FILE
           The $LINGUAS_FILE defines file(s) containing list of additional
           linguas to be processed by POInit, POUpdate or MOFiles builders. It
           also affects Translate builder. If the variable contains a string,
           it defines name of the list file. The $LINGUAS_FILE may be a list
           of file names as well. If $LINGUAS_FILE is set to True (or non-zero
           numeric value), the list will be read from default file named
           LINGUAS.

       LINK
           The linker.

       LINKCOM
           The command line used to link object files into an executable.

       LINKCOMSTR
           The string displayed when object files are linked into an
           executable. If this is not set, then $LINKCOM (the command line) is
           displayed.

               env = Environment(LINKCOMSTR = "Linking $TARGET")

       LINKFLAGS
           General user options passed to the linker. Note that this variable
           should not contain -l (or similar) options for linking with the
           libraries listed in $LIBS, nor -L (or similar) library search path
           options that scons generates automatically from $LIBPATH. See
           $_LIBFLAGS above, for the variable that expands to library-link
           options, and $_LIBDIRFLAGS above, for the variable that expands to
           library search path options.

       M4
           The M4 macro preprocessor.

       M4COM
           The command line used to pass files through the M4 macro
           preprocessor.

       M4COMSTR
           The string displayed when a file is passed through the M4 macro
           preprocessor. If this is not set, then $M4COM (the command line) is
           displayed.

       M4FLAGS
           General options passed to the M4 macro preprocessor.

       MAKEINDEX
           The makeindex generator for the TeX formatter and typesetter and
           the LaTeX structured formatter and typesetter.

       MAKEINDEXCOM
           The command line used to call the makeindex generator for the TeX
           formatter and typesetter and the LaTeX structured formatter and
           typesetter.

       MAKEINDEXCOMSTR
           The string displayed when calling the makeindex generator for the
           TeX formatter and typesetter and the LaTeX structured formatter and
           typesetter. If this is not set, then $MAKEINDEXCOM (the command
           line) is displayed.

       MAKEINDEXFLAGS
           General options passed to the makeindex generator for the TeX
           formatter and typesetter and the LaTeX structured formatter and
           typesetter.

       MAXLINELENGTH
           The maximum number of characters allowed on an external command
           line. On Win32 systems, link lines longer than this many characters
           are linked via a temporary file name.

       MIDL
           The Microsoft IDL compiler.

       MIDLCOM
           The command line used to pass files to the Microsoft IDL compiler.

       MIDLCOMSTR
           The string displayed when the Microsoft IDL copmiler is called. If
           this is not set, then $MIDLCOM (the command line) is displayed.

       MIDLFLAGS
           General options passed to the Microsoft IDL compiler.

       MOSUFFIX
           Suffix used for MO files (default: '.mo'). See msgfmt tool and
           MOFiles builder.

       MSGFMT
           Absolute path to msgfmt(1) binary, found by Detect(). See msgfmt
           tool and MOFiles builder.

       MSGFMTCOM
           Complete command line to run msgfmt(1) program. See msgfmt tool and
           MOFiles builder.

       MSGFMTCOMSTR
           String to display when msgfmt(1) is invoked (default: '', which
           means ``print $MSGFMTCOM''). See msgfmt tool and MOFiles builder.

       MSGFMTFLAGS
           Additional flags to msgfmt(1). See msgfmt tool and MOFiles builder.

       MSGINIT
           Path to msginit(1) program (found via Detect()). See msginit tool
           and POInit builder.

       MSGINITCOM
           Complete command line to run msginit(1) program. See msginit tool
           and POInit builder.

       MSGINITCOMSTR
           String to display when msginit(1) is invoked (default: '', which
           means ``print $MSGINITCOM''). See msginit tool and POInit builder.

       MSGINITFLAGS
           List of additional flags to msginit(1) (default: []). See msginit
           tool and POInit builder.

       _MSGINITLOCALE
           Internal ``macro''. Computes locale (language) name based on target
           filename (default: '${TARGET.filebase}').

           See msginit tool and POInit builder.

       MSGMERGE
           Absolute path to msgmerge(1) binary as found by Detect(). See
           msgmerge tool and POUpdate builder.

       MSGMERGECOM
           Complete command line to run msgmerge(1) command. See msgmerge tool
           and POUpdate builder.

       MSGMERGECOMSTR
           String to be displayed when msgmerge(1) is invoked (default: '',
           which means ``print $MSGMERGECOM''). See msgmerge tool and POUpdate
           builder.

       MSGMERGEFLAGS
           Additional flags to msgmerge(1) command. See msgmerge tool and
           POUpdate builder.

       MSSDK_DIR
           The directory containing the Microsoft SDK (either Platform SDK or
           Windows SDK) to be used for compilation.

       MSSDK_VERSION
           The version string of the Microsoft SDK (either Platform SDK or
           Windows SDK) to be used for compilation. Supported versions include
           6.1, 6.0A, 6.0, 2003R2 and 2003R1.

       MSVC_BATCH
           When set to any true value, specifies that SCons should batch
           compilation of object files when calling the Microsoft Visual C/C++
           compiler. All compilations of source files from the same source
           directory that generate target files in a same output directory and
           were configured in SCons using the same construction environment
           will be built in a single call to the compiler. Only source files
           that have changed since their object files were built will be
           passed to each compiler invocation (via the $CHANGED_SOURCES
           construction variable). Any compilations where the object (target)
           file base name (minus the .obj) does not match the source file base
           name will be compiled separately.

       MSVC_USE_SCRIPT
           Use a batch script to set up Microsoft Visual Studio compiler


           $MSVC_USE_SCRIPT overrides $MSVC_VERSION and $TARGET_ARCH. If set
           to the name of a Visual Studio .bat file (e.g. vcvars.bat), SCons
           will run that bat file and extract the relevant variables from the
           result (typically %INCLUDE%, %LIB%, and %PATH%). Setting
           MSVC_USE_SCRIPT to None bypasses the Visual Studio autodetection
           entirely; use this if you are running SCons in a Visual Studio cmd
           window and importing the shell's environment variables.

       MSVC_VERSION
           Sets the preferred version of Microsoft Visual C/C++ to use.

           If $MSVC_VERSION is not set, SCons will (by default) select the
           latest version of Visual C/C++ installed on your system. If the
           specified version isn't installed, tool initialization will fail.
           This variable must be passed as an argument to the Environment()
           constructor; setting it later has no effect.

           Valid values for Windows are 12.0, 12.0Exp, 11.0, 11.0Exp, 10.0,
           10.0Exp, 9.0, 9.0Exp, 8.0, 8.0Exp, 7.1, 7.0, and 6.0. Versions
           ending in Exp refer to "Express" or "Express for Desktop" editions.

       MSVS
           When the Microsoft Visual Studio tools are initialized, they set up
           this dictionary with the following keys:

           VERSION
               the version of MSVS being used (can be set via $MSVS_VERSION)

           VERSIONS
               the available versions of MSVS installed

           VCINSTALLDIR
               installed directory of Visual C++

           VSINSTALLDIR
               installed directory of Visual Studio

           FRAMEWORKDIR
               installed directory of the .NET framework

           FRAMEWORKVERSIONS
               list of installed versions of the .NET framework, sorted latest
               to oldest.

           FRAMEWORKVERSION
               latest installed version of the .NET framework

           FRAMEWORKSDKDIR
               installed location of the .NET SDK.

           PLATFORMSDKDIR
               installed location of the Platform SDK.

           PLATFORMSDK_MODULES
               dictionary of installed Platform SDK modules, where the
               dictionary keys are keywords for the various modules, and the
               values are 2-tuples where the first is the release date, and
               the second is the version number.

           If a value isn't set, it wasn't available in the registry.

       MSVS_ARCH
           Sets the architecture for which the generated project(s) should
           build.

           The default value is x86.  amd64 is also supported by SCons for
           some Visual Studio versions. Trying to set $MSVS_ARCH to an
           architecture that's not supported for a given Visual Studio version
           will generate an error.

       MSVS_PROJECT_GUID
           The string placed in a generated Microsoft Visual Studio project
           file as the value of the ProjectGUID attribute. There is no default
           value. If not defined, a new GUID is generated.

       MSVS_SCC_AUX_PATH
           The path name placed in a generated Microsoft Visual Studio project
           file as the value of the SccAuxPath attribute if the
           MSVS_SCC_PROVIDER construction variable is also set. There is no
           default value.

       MSVS_SCC_CONNECTION_ROOT
           The root path of projects in your SCC workspace, i.e the path under
           which all project and solution files will be generated. It is used
           as a reference path from which the relative paths of the generated
           Microsoft Visual Studio project and solution files are computed.
           The relative project file path is placed as the value of the
           SccLocalPath attribute of the project file and as the values of the
           SccProjectFilePathRelativizedFromConnection[i] (where [i] ranges
           from 0 to the number of projects in the solution) attributes of the
           GlobalSection(SourceCodeControl) section of the Microsoft Visual
           Studio solution file. Similarly the relative solution file path is
           placed as the values of the SccLocalPath[i] (where [i] ranges from
           0 to the number of projects in the solution) attributes of the
           GlobalSection(SourceCodeControl) section of the Microsoft Visual
           Studio solution file. This is used only if the MSVS_SCC_PROVIDER
           construction variable is also set. The default value is the current
           working directory.

       MSVS_SCC_PROJECT_NAME
           The project name placed in a generated Microsoft Visual Studio
           project file as the value of the SccProjectName attribute if the
           MSVS_SCC_PROVIDER construction variable is also set. In this case
           the string is also placed in the SccProjectName0 attribute of the
           GlobalSection(SourceCodeControl) section of the Microsoft Visual
           Studio solution file. There is no default value.

       MSVS_SCC_PROVIDER
           The string placed in a generated Microsoft Visual Studio project
           file as the value of the SccProvider attribute. The string is also
           placed in the SccProvider0 attribute of the
           GlobalSection(SourceCodeControl) section of the Microsoft Visual
           Studio solution file. There is no default value.

       MSVS_VERSION
           Sets the preferred version of Microsoft Visual Studio to use.

           If $MSVS_VERSION is not set, SCons will (by default) select the
           latest version of Visual Studio installed on your system. So, if
           you have version 6 and version 7 (MSVS .NET) installed, it will
           prefer version 7. You can override this by specifying the
           MSVS_VERSION variable in the Environment initialization, setting it
           to the appropriate version ('6.0' or '7.0', for example). If the
           specified version isn't installed, tool initialization will fail.

           This is obsolete: use $MSVC_VERSION instead. If $MSVS_VERSION is
           set and $MSVC_VERSION is not, $MSVC_VERSION will be set
           automatically to $MSVS_VERSION. If both are set to different
           values, scons will raise an error.

       MSVSBUILDCOM
           The build command line placed in a generated Microsoft Visual
           Studio project file. The default is to have Visual Studio invoke
           SCons with any specified build targets.

       MSVSCLEANCOM
           The clean command line placed in a generated Microsoft Visual
           Studio project file. The default is to have Visual Studio invoke
           SCons with the -c option to remove any specified targets.

       MSVSENCODING
           The encoding string placed in a generated Microsoft Visual Studio
           project file. The default is encoding Windows-1252.

       MSVSPROJECTCOM
           The action used to generate Microsoft Visual Studio project files.

       MSVSPROJECTSUFFIX
           The suffix used for Microsoft Visual Studio project (DSP) files.
           The default value is .vcproj when using Visual Studio version 7.x
           (.NET) or later version, and .dsp when using earlier versions of
           Visual Studio.

       MSVSREBUILDCOM
           The rebuild command line placed in a generated Microsoft Visual
           Studio project file. The default is to have Visual Studio invoke
           SCons with any specified rebuild targets.

       MSVSSCONS
           The SCons used in generated Microsoft Visual Studio project files.
           The default is the version of SCons being used to generate the
           project file.

       MSVSSCONSCOM
           The default SCons command used in generated Microsoft Visual Studio
           project files.

       MSVSSCONSCRIPT
           The sconscript file (that is, SConstruct or SConscript file) that
           will be invoked by Visual Studio project files (through the
           $MSVSSCONSCOM variable). The default is the same sconscript file
           that contains the call to MSVSProject to build the project file.

       MSVSSCONSFLAGS
           The SCons flags used in generated Microsoft Visual Studio project
           files.

       MSVSSOLUTIONCOM
           The action used to generate Microsoft Visual Studio solution files.

       MSVSSOLUTIONSUFFIX
           The suffix used for Microsoft Visual Studio solution (DSW) files.
           The default value is .sln when using Visual Studio version 7.x
           (.NET), and .dsw when using earlier versions of Visual Studio.

       MT
           The program used on Windows systems to embed manifests into DLLs
           and EXEs. See also $WINDOWS_EMBED_MANIFEST.

       MTEXECOM
           The Windows command line used to embed manifests into executables.
           See also $MTSHLIBCOM.

       MTFLAGS
           Flags passed to the $MT manifest embedding program (Windows only).

       MTSHLIBCOM
           The Windows command line used to embed manifests into shared
           libraries (DLLs). See also $MTEXECOM.

       MWCW_VERSION
           The version number of the MetroWerks CodeWarrior C compiler to be
           used.

       MWCW_VERSIONS
           A list of installed versions of the MetroWerks CodeWarrior C
           compiler on this system.

       NAME
           Specfies the name of the project to package.

       no_import_lib
           When set to non-zero, suppresses creation of a corresponding
           Windows static import lib by the SharedLibrary builder when used
           with MinGW, Microsoft Visual Studio or Metrowerks. This also
           suppresses creation of an export (.exp) file when using Microsoft
           Visual Studio.

       OBJPREFIX
           The prefix used for (static) object file names.

       OBJSUFFIX
           The suffix used for (static) object file names.

       P4
           The Perforce executable.

       P4COM
           The command line used to fetch source files from Perforce.

       P4COMSTR
           The string displayed when fetching a source file from Perforce. If
           this is not set, then $P4COM (the command line) is displayed.

       P4FLAGS
           General options that are passed to Perforce.

       PACKAGEROOT
           Specifies the directory where all files in resulting archive will
           be placed if applicable. The default value is "$NAME-$VERSION".

       PACKAGETYPE
           Selects the package type to build. Currently these are available:

           * msi - Microsoft Installer * rpm - Redhat Package Manger * ipkg -
           Itsy Package Management System * tarbz2 - compressed tar * targz -
           compressed tar * zip - zip file * src_tarbz2 - compressed tar
           source * src_targz - compressed tar source * src_zip - zip file
           source

           This may be overridden with the "package_type" command line option.

       PACKAGEVERSION
           The version of the package (not the underlying project). This is
           currently only used by the rpm packager and should reflect changes
           in the packaging, not the underlying project code itself.

       PCH
           The Microsoft Visual C++ precompiled header that will be used when
           compiling object files. This variable is ignored by tools other
           than Microsoft Visual C++. When this variable is defined SCons will
           add options to the compiler command line to cause it to use the
           precompiled header, and will also set up the dependencies for the
           PCH file. Example:

               env['PCH'] = 'StdAfx.pch'

       PCHCOM
           The command line used by the PCH builder to generated a precompiled
           header.

       PCHCOMSTR
           The string displayed when generating a precompiled header. If this
           is not set, then $PCHCOM (the command line) is displayed.

       PCHPDBFLAGS
           A construction variable that, when expanded, adds the /yD flag to
           the command line only if the $PDB construction variable is set.

       PCHSTOP
           This variable specifies how much of a source file is precompiled.
           This variable is ignored by tools other than Microsoft Visual C++,
           or when the PCH variable is not being used. When this variable is
           define it must be a string that is the name of the header that is
           included at the end of the precompiled portion of the source files,
           or the empty string if the "#pragma hrdstop" construct is being
           used:

               env['PCHSTOP'] = 'StdAfx.h'

       PDB
           The Microsoft Visual C++ PDB file that will store debugging
           information for object files, shared libraries, and programs. This
           variable is ignored by tools other than Microsoft Visual C++. When
           this variable is defined SCons will add options to the compiler and
           linker command line to cause them to generate external debugging
           information, and will also set up the dependencies for the PDB
           file. Example:

               env['PDB'] = 'hello.pdb'

           The Visual C++ compiler switch that SCons uses by default to
           generate PDB information is /Z7. This works correctly with parallel
           (-j) builds because it embeds the debug information in the
           intermediate object files, as opposed to sharing a single PDB file
           between multiple object files. This is also the only way to get
           debug information embedded into a static library. Using the /Zi
           instead may yield improved link-time performance, although parallel
           builds will no longer work. You can generate PDB files with the /Zi
           switch by overriding the default $CCPDBFLAGS variable; see the
           entry for that variable for specific examples.

       PDFCOM
           A deprecated synonym for $DVIPDFCOM.

       PDFLATEX
           The pdflatex utility.

       PDFLATEXCOM
           The command line used to call the pdflatex utility.

       PDFLATEXCOMSTR
           The string displayed when calling the pdflatex utility. If this is
           not set, then $PDFLATEXCOM (the command line) is displayed.

               env = Environment(PDFLATEX;COMSTR = "Building $TARGET from LaTeX input $SOURCES")

       PDFLATEXFLAGS
           General options passed to the pdflatex utility.

       PDFPREFIX
           The prefix used for PDF file names.

       PDFSUFFIX
           The suffix used for PDF file names.

       PDFTEX
           The pdftex utility.

       PDFTEXCOM
           The command line used to call the pdftex utility.

       PDFTEXCOMSTR
           The string displayed when calling the pdftex utility. If this is
           not set, then $PDFTEXCOM (the command line) is displayed.

               env = Environment(PDFTEXCOMSTR = "Building $TARGET from TeX input $SOURCES")

       PDFTEXFLAGS
           General options passed to the pdftex utility.

       PKGCHK
           On Solaris systems, the package-checking program that will be used
           (along with $PKGINFO) to look for installed versions of the Sun PRO
           C++ compiler. The default is /usr/sbin/pgkchk.

       PKGINFO
           On Solaris systems, the package information program that will be
           used (along with $PKGCHK) to look for installed versions of the Sun
           PRO C++ compiler. The default is pkginfo.

       PLATFORM
           The name of the platform used to create the Environment. If no
           platform is specified when the Environment is created, scons
           autodetects the platform.

               env = Environment(tools = [])
               if env['PLATFORM'] == 'cygwin':
                   Tool('mingw')(env)
               else:
                   Tool('msvc')(env)

       POAUTOINIT
           The $POAUTOINIT variable, if set to True (on non-zero numeric
           value), let the msginit tool to automatically initialize missing PO
           files with msginit(1). This applies to both, POInit and POUpdate
           builders (and others that use any of them).

       POCREATE_ALIAS
           Common alias for all PO files created with POInit builder (default:
           'po-create'). See msginit tool and POInit builder.

       POSUFFIX
           Suffix used for PO files (default: '.po') See msginit tool and
           POInit builder.

       POTDOMAIN
           The $POTDOMAIN defines default domain, used to generate POT
           filename as $POTDOMAIN.pot when no POT file name is provided by the
           user. This applies to POTUpdate, POInit and POUpdate builders (and
           builders, that use them, e.g.  Translate). Normally (if $POTDOMAIN
           is not defined), the builders use messages.pot as default POT file
           name.

       POTSUFFIX
           Suffix used for PO Template files (default: '.pot'). See xgettext
           tool and POTUpdate builder.

       POTUPDATE_ALIAS
           Name of the common phony target for all PO Templates created with
           POUpdate (default: 'pot-update'). See xgettext tool and POTUpdate
           builder.

       POUPDATE_ALIAS
           Common alias for all PO files being defined with POUpdate builder
           (default: 'po-update'). See msgmerge tool and POUpdate builder.

       PRINT_CMD_LINE_FUNC
           A Python function used to print the command lines as they are
           executed (assuming command printing is not disabled by the -q or -s
           options or their equivalents). The function should take four
           arguments: s, the command being executed (a string), target, the
           target being built (file node, list, or string name(s)), source,
           the source(s) used (file node, list, or string name(s)), and env,
           the environment being used.

           The function must do the printing itself. The default
           implementation, used if this variable is not set or is None, is:

               def print_cmd_line(s, target, source, env):
                 sys.stdout.write(s + "\n")

           Here's an example of a more interesting function:

               def print_cmd_line(s, target, source, env):
                  sys.stdout.write("Building %s -> %s...\n" %
                   (' and '.join([str(x) for x in source]),
                    ' and '.join([str(x) for x in target])))
               env=Environment(PRINT_CMD_LINE_FUNC=print_cmd_line)
               env.Program('foo', 'foo.c')

           This just prints "Building targetname from sourcename..." instead
           of the actual commands. Such a function could also log the actual
           commands to a log file, for example.

       PROGEMITTER
           TODO

       PROGPREFIX
           The prefix used for executable file names.

       PROGSUFFIX
           The suffix used for executable file names.

       PSCOM
           The command line used to convert TeX DVI files into a PostScript
           file.

       PSCOMSTR
           The string displayed when a TeX DVI file is converted into a
           PostScript file. If this is not set, then $PSCOM (the command line)
           is displayed.

       PSPREFIX
           The prefix used for PostScript file names.

       PSSUFFIX
           The prefix used for PostScript file names.

       QT_AUTOSCAN
           Turn off scanning for mocable files. Use the Moc Builder to
           explicitly specify files to run moc on.

       QT_BINPATH
           The path where the qt binaries are installed. The default value is
           '$QTDIR/bin'.

       QT_CPPPATH
           The path where the qt header files are installed. The default value
           is '$QTDIR/include'. Note: If you set this variable to None, the
           tool won't change the $CPPPATH construction variable.

       QT_DEBUG
           Prints lots of debugging information while scanning for moc files.

       QT_LIB
           Default value is 'qt'. You may want to set this to 'qt-mt'. Note:
           If you set this variable to None, the tool won't change the $LIBS
           variable.

       QT_LIBPATH
           The path where the qt libraries are installed. The default value is
           '$QTDIR/lib'. Note: If you set this variable to None, the tool
           won't change the $LIBPATH construction variable.

       QT_MOC
           Default value is '$QT_BINPATH/moc'.

       QT_MOCCXXPREFIX
           Default value is ''. Prefix for moc output files, when source is a
           cxx file.

       QT_MOCCXXSUFFIX
           Default value is '.moc'. Suffix for moc output files, when source
           is a cxx file.

       QT_MOCFROMCXXCOM
           Command to generate a moc file from a cpp file.

       QT_MOCFROMCXXCOMSTR
           The string displayed when generating a moc file from a cpp file. If
           this is not set, then $QT_MOCFROMCXXCOM (the command line) is
           displayed.

       QT_MOCFROMCXXFLAGS
           Default value is '-i'. These flags are passed to moc, when moccing
           a C++ file.

       QT_MOCFROMHCOM
           Command to generate a moc file from a header.

       QT_MOCFROMHCOMSTR
           The string displayed when generating a moc file from a cpp file. If
           this is not set, then $QT_MOCFROMHCOM (the command line) is
           displayed.

       QT_MOCFROMHFLAGS
           Default value is ''. These flags are passed to moc, when moccing a
           header file.

       QT_MOCHPREFIX
           Default value is 'moc_'. Prefix for moc output files, when source
           is a header.

       QT_MOCHSUFFIX
           Default value is '$CXXFILESUFFIX'. Suffix for moc output files,
           when source is a header.

       QT_UIC
           Default value is '$QT_BINPATH/uic'.

       QT_UICCOM
           Command to generate header files from .ui files.

       QT_UICCOMSTR
           The string displayed when generating header files from .ui files.
           If this is not set, then $QT_UICCOM (the command line) is
           displayed.

       QT_UICDECLFLAGS
           Default value is ''. These flags are passed to uic, when creating a
           a h file from a .ui file.

       QT_UICDECLPREFIX
           Default value is ''. Prefix for uic generated header files.

       QT_UICDECLSUFFIX
           Default value is '.h'. Suffix for uic generated header files.

       QT_UICIMPLFLAGS
           Default value is ''. These flags are passed to uic, when creating a
           cxx file from a .ui file.

       QT_UICIMPLPREFIX
           Default value is 'uic_'. Prefix for uic generated implementation
           files.

       QT_UICIMPLSUFFIX
           Default value is '$CXXFILESUFFIX'. Suffix for uic generated
           implementation files.

       QT_UISUFFIX
           Default value is '.ui'. Suffix of designer input files.

       QTDIR
           The qt tool tries to take this from os.environ. It also initializes
           all QT_* construction variables listed below. (Note that all paths
           are constructed with python's os.path.join() method, but are listed
           here with the '/' separator for easier reading.) In addition, the
           construction environment variables $CPPPATH, $LIBPATH and $LIBS may
           be modified and the variables $PROGEMITTER, $SHLIBEMITTER and
           $LIBEMITTER are modified. Because the build-performance is affected
           when using this tool, you have to explicitly specify it at
           Environment creation:

               Environment(tools=['default','qt'])

           The qt tool supports the following operations:


           Automatic moc file generation from header files.  You do not have
           to specify moc files explicitly, the tool does it for you. However,
           there are a few preconditions to do so: Your header file must have
           the same filebase as your implementation file and must stay in the
           same directory. It must have one of the suffixes .h, .hpp, .H,
           .hxx, .hh. You can turn off automatic moc file generation by
           setting QT_AUTOSCAN to 0. See also the corresponding Moc() builder
           method.


           Automatic moc file generation from cxx files.  As stated in the qt
           documentation, include the moc file at the end of the cxx file.
           Note that you have to include the file, which is generated by the
           transformation ${QT_MOCCXXPREFIX}<basename>${QT_MOCCXXSUFFIX}, by
           default <basename>.moc. A warning is generated after building the
           moc file, if you do not include the correct file. If you are using
           VariantDir, you may need to specify duplicate=1. You can turn off
           automatic moc file generation by setting QT_AUTOSCAN to 0. See also
           the corresponding Moc builder method.


           Automatic handling of .ui files.  The implementation files
           generated from .ui files are handled much the same as yacc or lex
           files. Each .ui file given as a source of Program, Library or
           SharedLibrary will generate three files, the declaration file, the
           implementation file and a moc file. Because there are also
           generated headers, you may need to specify duplicate=1 in calls to
           VariantDir. See also the corresponding Uic builder method.

       RANLIB
           The archive indexer.

       RANLIBCOM
           The command line used to index a static library archive.

       RANLIBCOMSTR
           The string displayed when a static library archive is indexed. If
           this is not set, then $RANLIBCOM (the command line) is displayed.

               env = Environment(RANLIBCOMSTR = "Indexing $TARGET")

       RANLIBFLAGS
           General options passed to the archive indexer.

       RC
           The resource compiler used to build a Microsoft Visual C++ resource
           file.

       RCCOM
           The command line used to build a Microsoft Visual C++ resource
           file.

       RCCOMSTR
           The string displayed when invoking the resource compiler to build a
           Microsoft Visual C++ resource file. If this is not set, then $RCCOM
           (the command line) is displayed.

       RCFLAGS
           The flags passed to the resource compiler by the RES builder.

       RCINCFLAGS
           An automatically-generated construction variable containing the
           command-line options for specifying directories to be searched by
           the resource compiler. The value of $RCINCFLAGS is created by
           appending $RCINCPREFIX and $RCINCSUFFIX to the beginning and end of
           each directory in $CPPPATH.

       RCINCPREFIX
           The prefix (flag) used to specify an include directory on the
           resource compiler command line. This will be appended to the
           beginning of each directory in the $CPPPATH construction variable
           when the $RCINCFLAGS variable is expanded.

       RCINCSUFFIX
           The suffix used to specify an include directory on the resource
           compiler command line. This will be appended to the end of each
           directory in the $CPPPATH construction variable when the
           $RCINCFLAGS variable is expanded.

       RCS
           The RCS executable. Note that this variable is not actually used
           for the command to fetch source files from RCS; see the $RCS_CO
           construction variable, below.

       RCS_CO
           The RCS "checkout" executable, used to fetch source files from RCS.

       RCS_COCOM
           The command line used to fetch (checkout) source files from RCS.

       RCS_COCOMSTR
           The string displayed when fetching a source file from RCS. If this
           is not set, then $RCS_COCOM (the command line) is displayed.

       RCS_COFLAGS
           Options that are passed to the $RCS_CO command.

       RDirs
           A function that converts a string into a list of Dir instances by
           searching the repositories.

       REGSVR
           The program used on Windows systems to register a newly-built DLL
           library whenever the SharedLibrary builder is passed a keyword
           argument of register=1.

       REGSVRCOM
           The command line used on Windows systems to register a newly-built
           DLL library whenever the SharedLibrary builder is passed a keyword
           argument of register=1.

       REGSVRCOMSTR
           The string displayed when registering a newly-built DLL file. If
           this is not set, then $REGSVRCOM (the command line) is displayed.

       REGSVRFLAGS
           Flags passed to the DLL registration program on Windows systems
           when a newly-built DLL library is registered. By default, this
           includes the /s that prevents dialog boxes from popping up and
           requiring user attention.

       RMIC
           The Java RMI stub compiler.

       RMICCOM
           The command line used to compile stub and skeleton class files from
           Java classes that contain RMI implementations. Any options
           specified in the $RMICFLAGS construction variable are included on
           this command line.

       RMICCOMSTR
           The string displayed when compiling stub and skeleton class files
           from Java classes that contain RMI implementations. If this is not
           set, then $RMICCOM (the command line) is displayed.

               env = Environment(RMICCOMSTR = "Generating stub/skeleton class files $TARGETS from $SOURCES")

       RMICFLAGS
           General options passed to the Java RMI stub compiler.

       _RPATH
           An automatically-generated construction variable containing the
           rpath flags to be used when linking a program with shared
           libraries. The value of $_RPATH is created by appending
           $RPATHPREFIX and $RPATHSUFFIX to the beginning and end of each
           directory in $RPATH.

       RPATH
           A list of paths to search for shared libraries when running
           programs. Currently only used in the GNU (gnulink), IRIX (sgilink)
           and Sun (sunlink) linkers. Ignored on platforms and toolchains that
           don't support it. Note that the paths added to RPATH are not
           transformed by scons in any way: if you want an absolute path, you
           must make it absolute yourself.

       RPATHPREFIX
           The prefix used to specify a directory to be searched for shared
           libraries when running programs. This will be appended to the
           beginning of each directory in the $RPATH construction variable
           when the $_RPATH variable is automatically generated.

       RPATHSUFFIX
           The suffix used to specify a directory to be searched for shared
           libraries when running programs. This will be appended to the end
           of each directory in the $RPATH construction variable when the
           $_RPATH variable is automatically generated.

       RPCGEN
           The RPC protocol compiler.

       RPCGENCLIENTFLAGS
           Options passed to the RPC protocol compiler when generating client
           side stubs. These are in addition to any flags specified in the
           $RPCGENFLAGS construction variable.

       RPCGENFLAGS
           General options passed to the RPC protocol compiler.

       RPCGENHEADERFLAGS
           Options passed to the RPC protocol compiler when generating a
           header file. These are in addition to any flags specified in the
           $RPCGENFLAGS construction variable.

       RPCGENSERVICEFLAGS
           Options passed to the RPC protocol compiler when generating server
           side stubs. These are in addition to any flags specified in the
           $RPCGENFLAGS construction variable.

       RPCGENXDRFLAGS
           Options passed to the RPC protocol compiler when generating XDR
           routines. These are in addition to any flags specified in the
           $RPCGENFLAGS construction variable.

       SCANNERS
           A list of the available implicit dependency scanners. New file
           scanners may be added by appending to this list, although the more
           flexible approach is to associate scanners with a specific Builder.
           See the sections "Builder Objects" and "Scanner Objects," below,
           for more information.

       SCCS
           The SCCS executable.

       SCCSCOM
           The command line used to fetch source files from SCCS.

       SCCSCOMSTR
           The string displayed when fetching a source file from a CVS
           repository. If this is not set, then $SCCSCOM (the command line) is
           displayed.

       SCCSFLAGS
           General options that are passed to SCCS.

       SCCSGETFLAGS
           Options that are passed specifically to the SCCS "get" subcommand.
           This can be set, for example, to -e to check out editable files
           from SCCS.

       SCONS_HOME
           The (optional) path to the SCons library directory, initialized
           from the external environment. If set, this is used to construct a
           shorter and more efficient search path in the $MSVSSCONS command
           line executed from Microsoft Visual Studio project files.

       SHCC
           The C compiler used for generating shared-library objects.

       SHCCCOM
           The command line used to compile a C source file to a
           shared-library object file. Any options specified in the $SHCFLAGS,
           $SHCCFLAGS and $CPPFLAGS construction variables are included on
           this command line.

       SHCCCOMSTR
           The string displayed when a C source file is compiled to a shared
           object file. If this is not set, then $SHCCCOM (the command line)
           is displayed.

               env = Environment(SHCCCOMSTR = "Compiling shared object $TARGET")

       SHCCFLAGS
           Options that are passed to the C and C++ compilers to generate
           shared-library objects.

       SHCFLAGS
           Options that are passed to the C compiler (only; not C++) to
           generate shared-library objects.

       SHCXX
           The C++ compiler used for generating shared-library objects.

       SHCXXCOM
           The command line used to compile a C++ source file to a
           shared-library object file. Any options specified in the
           $SHCXXFLAGS and $CPPFLAGS construction variables are included on
           this command line.

       SHCXXCOMSTR
           The string displayed when a C++ source file is compiled to a shared
           object file. If this is not set, then $SHCXXCOM (the command line)
           is displayed.

               env = Environment(SHCXXCOMSTR = "Compiling shared object $TARGET")

       SHCXXFLAGS
           Options that are passed to the C++ compiler to generate
           shared-library objects.

       SHDC
           SHDC.

       SHDCOM
           SHDCOM.

       SHDLINK
           SHDLINK.

       SHDLINKCOM
           SHDLINKCOM.

       SHDLINKFLAGS
           SHDLINKFLAGS.

       SHELL
           A string naming the shell program that will be passed to the $SPAWN
           function. See the $SPAWN construction variable for more
           information.

       SHF03
           The Fortran 03 compiler used for generating shared-library objects.
           You should normally set the $SHFORTRAN variable, which specifies
           the default Fortran compiler for all Fortran versions. You only
           need to set $SHF03 if you need to use a specific compiler or
           compiler version for Fortran 03 files.

       SHF03COM
           The command line used to compile a Fortran 03 source file to a
           shared-library object file. You only need to set $SHF03COM if you
           need to use a specific command line for Fortran 03 files. You
           should normally set the $SHFORTRANCOM variable, which specifies the
           default command line for all Fortran versions.

       SHF03COMSTR
           The string displayed when a Fortran 03 source file is compiled to a
           shared-library object file. If this is not set, then $SHF03COM or
           $SHFORTRANCOM (the command line) is displayed.

       SHF03FLAGS
           Options that are passed to the Fortran 03 compiler to generated
           shared-library objects. You only need to set $SHF03FLAGS if you
           need to define specific user options for Fortran 03 files. You
           should normally set the $SHFORTRANFLAGS variable, which specifies
           the user-specified options passed to the default Fortran compiler
           for all Fortran versions.

       SHF03PPCOM
           The command line used to compile a Fortran 03 source file to a
           shared-library object file after first running the file through the
           C preprocessor. Any options specified in the $SHF03FLAGS and
           $CPPFLAGS construction variables are included on this command line.
           You only need to set $SHF03PPCOM if you need to use a specific
           C-preprocessor command line for Fortran 03 files. You should
           normally set the $SHFORTRANPPCOM variable, which specifies the
           default C-preprocessor command line for all Fortran versions.

       SHF03PPCOMSTR
           The string displayed when a Fortran 03 source file is compiled to a
           shared-library object file after first running the file through the
           C preprocessor. If this is not set, then $SHF03PPCOM or
           $SHFORTRANPPCOM (the command line) is displayed.

       SHF08
           The Fortran 08 compiler used for generating shared-library objects.
           You should normally set the $SHFORTRAN variable, which specifies
           the default Fortran compiler for all Fortran versions. You only
           need to set $SHF08 if you need to use a specific compiler or
           compiler version for Fortran 08 files.

       SHF08COM
           The command line used to compile a Fortran 08 source file to a
           shared-library object file. You only need to set $SHF08COM if you
           need to use a specific command line for Fortran 08 files. You
           should normally set the $SHFORTRANCOM variable, which specifies the
           default command line for all Fortran versions.

       SHF08COMSTR
           The string displayed when a Fortran 08 source file is compiled to a
           shared-library object file. If this is not set, then $SHF08COM or
           $SHFORTRANCOM (the command line) is displayed.

       SHF08FLAGS
           Options that are passed to the Fortran 08 compiler to generated
           shared-library objects. You only need to set $SHF08FLAGS if you
           need to define specific user options for Fortran 08 files. You
           should normally set the $SHFORTRANFLAGS variable, which specifies
           the user-specified options passed to the default Fortran compiler
           for all Fortran versions.

       SHF08PPCOM
           The command line used to compile a Fortran 08 source file to a
           shared-library object file after first running the file through the
           C preprocessor. Any options specified in the $SHF08FLAGS and
           $CPPFLAGS construction variables are included on this command line.
           You only need to set $SHF08PPCOM if you need to use a specific
           C-preprocessor command line for Fortran 08 files. You should
           normally set the $SHFORTRANPPCOM variable, which specifies the
           default C-preprocessor command line for all Fortran versions.

       SHF08PPCOMSTR
           The string displayed when a Fortran 08 source file is compiled to a
           shared-library object file after first running the file through the
           C preprocessor. If this is not set, then $SHF08PPCOM or
           $SHFORTRANPPCOM (the command line) is displayed.

       SHF77
           The Fortran 77 compiler used for generating shared-library objects.
           You should normally set the $SHFORTRAN variable, which specifies
           the default Fortran compiler for all Fortran versions. You only
           need to set $SHF77 if you need to use a specific compiler or
           compiler version for Fortran 77 files.

       SHF77COM
           The command line used to compile a Fortran 77 source file to a
           shared-library object file. You only need to set $SHF77COM if you
           need to use a specific command line for Fortran 77 files. You
           should normally set the $SHFORTRANCOM variable, which specifies the
           default command line for all Fortran versions.

       SHF77COMSTR
           The string displayed when a Fortran 77 source file is compiled to a
           shared-library object file. If this is not set, then $SHF77COM or
           $SHFORTRANCOM (the command line) is displayed.

       SHF77FLAGS
           Options that are passed to the Fortran 77 compiler to generated
           shared-library objects. You only need to set $SHF77FLAGS if you
           need to define specific user options for Fortran 77 files. You
           should normally set the $SHFORTRANFLAGS variable, which specifies
           the user-specified options passed to the default Fortran compiler
           for all Fortran versions.

       SHF77PPCOM
           The command line used to compile a Fortran 77 source file to a
           shared-library object file after first running the file through the
           C preprocessor. Any options specified in the $SHF77FLAGS and
           $CPPFLAGS construction variables are included on this command line.
           You only need to set $SHF77PPCOM if you need to use a specific
           C-preprocessor command line for Fortran 77 files. You should
           normally set the $SHFORTRANPPCOM variable, which specifies the
           default C-preprocessor command line for all Fortran versions.

       SHF77PPCOMSTR
           The string displayed when a Fortran 77 source file is compiled to a
           shared-library object file after first running the file through the
           C preprocessor. If this is not set, then $SHF77PPCOM or
           $SHFORTRANPPCOM (the command line) is displayed.

       SHF90
           The Fortran 90 compiler used for generating shared-library objects.
           You should normally set the $SHFORTRAN variable, which specifies
           the default Fortran compiler for all Fortran versions. You only
           need to set $SHF90 if you need to use a specific compiler or
           compiler version for Fortran 90 files.

       SHF90COM
           The command line used to compile a Fortran 90 source file to a
           shared-library object file. You only need to set $SHF90COM if you
           need to use a specific command line for Fortran 90 files. You
           should normally set the $SHFORTRANCOM variable, which specifies the
           default command line for all Fortran versions.

       SHF90COMSTR
           The string displayed when a Fortran 90 source file is compiled to a
           shared-library object file. If this is not set, then $SHF90COM or
           $SHFORTRANCOM (the command line) is displayed.

       SHF90FLAGS
           Options that are passed to the Fortran 90 compiler to generated
           shared-library objects. You only need to set $SHF90FLAGS if you
           need to define specific user options for Fortran 90 files. You
           should normally set the $SHFORTRANFLAGS variable, which specifies
           the user-specified options passed to the default Fortran compiler
           for all Fortran versions.

       SHF90PPCOM
           The command line used to compile a Fortran 90 source file to a
           shared-library object file after first running the file through the
           C preprocessor. Any options specified in the $SHF90FLAGS and
           $CPPFLAGS construction variables are included on this command line.
           You only need to set $SHF90PPCOM if you need to use a specific
           C-preprocessor command line for Fortran 90 files. You should
           normally set the $SHFORTRANPPCOM variable, which specifies the
           default C-preprocessor command line for all Fortran versions.

       SHF90PPCOMSTR
           The string displayed when a Fortran 90 source file is compiled to a
           shared-library object file after first running the file through the
           C preprocessor. If this is not set, then $SHF90PPCOM or
           $SHFORTRANPPCOM (the command line) is displayed.

       SHF95
           The Fortran 95 compiler used for generating shared-library objects.
           You should normally set the $SHFORTRAN variable, which specifies
           the default Fortran compiler for all Fortran versions. You only
           need to set $SHF95 if you need to use a specific compiler or
           compiler version for Fortran 95 files.

       SHF95COM
           The command line used to compile a Fortran 95 source file to a
           shared-library object file. You only need to set $SHF95COM if you
           need to use a specific command line for Fortran 95 files. You
           should normally set the $SHFORTRANCOM variable, which specifies the
           default command line for all Fortran versions.

       SHF95COMSTR
           The string displayed when a Fortran 95 source file is compiled to a
           shared-library object file. If this is not set, then $SHF95COM or
           $SHFORTRANCOM (the command line) is displayed.

       SHF95FLAGS
           Options that are passed to the Fortran 95 compiler to generated
           shared-library objects. You only need to set $SHF95FLAGS if you
           need to define specific user options for Fortran 95 files. You
           should normally set the $SHFORTRANFLAGS variable, which specifies
           the user-specified options passed to the default Fortran compiler
           for all Fortran versions.

       SHF95PPCOM
           The command line used to compile a Fortran 95 source file to a
           shared-library object file after first running the file through the
           C preprocessor. Any options specified in the $SHF95FLAGS and
           $CPPFLAGS construction variables are included on this command line.
           You only need to set $SHF95PPCOM if you need to use a specific
           C-preprocessor command line for Fortran 95 files. You should
           normally set the $SHFORTRANPPCOM variable, which specifies the
           default C-preprocessor command line for all Fortran versions.

       SHF95PPCOMSTR
           The string displayed when a Fortran 95 source file is compiled to a
           shared-library object file after first running the file through the
           C preprocessor. If this is not set, then $SHF95PPCOM or
           $SHFORTRANPPCOM (the command line) is displayed.

       SHFORTRAN
           The default Fortran compiler used for generating shared-library
           objects.

       SHFORTRANCOM
           The command line used to compile a Fortran source file to a
           shared-library object file.

       SHFORTRANCOMSTR
           The string displayed when a Fortran source file is compiled to a
           shared-library object file. If this is not set, then $SHFORTRANCOM
           (the command line) is displayed.

       SHFORTRANFLAGS
           Options that are passed to the Fortran compiler to generate
           shared-library objects.

       SHFORTRANPPCOM
           The command line used to compile a Fortran source file to a
           shared-library object file after first running the file through the
           C preprocessor. Any options specified in the $SHFORTRANFLAGS and
           $CPPFLAGS construction variables are included on this command line.

       SHFORTRANPPCOMSTR
           The string displayed when a Fortran source file is compiled to a
           shared-library object file after first running the file through the
           C preprocessor. If this is not set, then $SHFORTRANPPCOM (the
           command line) is displayed.

       SHLIBEMITTER
           TODO

       SHLIBNOVERSIONSYMLINKS
           Instructs the SharedLibrary builder to not create symlinks for
           versioned shared libraries.

       SHLIBPREFIX
           The prefix used for shared library file names.

       _SHLIBSONAME
           A macro that automatically generates shared library's SONAME based
           on $TARGET, $SHLIBVERSION and $SHLIBSUFFIX. Used by SharedLibrary
           builder when the linker tool supports SONAME (e.g.  gnulink).

       SHLIBSUFFIX
           The suffix used for shared library file names.

       SHLIBVERSION
           When this construction variable is defined, a versioned shared
           library is created by SharedLibrary builder. This activates the
           $_SHLIBVERSIONFLAGS and thus modifies the $SHLINKCOM as required,
           adds the version number to the library name, and creates the
           symlinks that are needed.  $SHLIBVERSION versions should exist as
           alpha-numeric, decimal-delimited values as defined by the regular
           expression "\w+[\.\w+]*". Example $SHLIBVERSION values include '1',
           '1.2.3', and '1.2.gitaa412c8b'.

       _SHLIBVERSIONFLAGS
           This macro automatically introduces extra flags to $SHLINKCOM when
           building versioned SharedLibrary (that is when $SHLIBVERSION is
           set).  _SHLIBVERSIONFLAGS usually adds $SHLIBVERSIONFLAGS and some
           extra dynamically generated options (such as
           -Wl,-soname=$_SHLIBSONAME. It is unused by "plain" (unversioned)
           shared libraries.

       SHLIBVERSIONFLAGS
           Extra flags added to $SHLINKCOM when building versioned
           SharedLibrary. These flags are only used when $SHLIBVERSION is set.

       SHLINK
           The linker for programs that use shared libraries.

       SHLINKCOM
           The command line used to link programs using shared libraries.

       SHLINKCOMSTR
           The string displayed when programs using shared libraries are
           linked. If this is not set, then $SHLINKCOM (the command line) is
           displayed.

               env = Environment(SHLINKCOMSTR = "Linking shared $TARGET")

       SHLINKFLAGS
           General user options passed to the linker for programs using shared
           libraries. Note that this variable should not contain -l (or
           similar) options for linking with the libraries listed in $LIBS,
           nor -L (or similar) include search path options that scons
           generates automatically from $LIBPATH. See $_LIBFLAGS above, for
           the variable that expands to library-link options, and
           $_LIBDIRFLAGS above, for the variable that expands to library
           search path options.

       SHOBJPREFIX
           The prefix used for shared object file names.

       SHOBJSUFFIX
           The suffix used for shared object file names.

       SONAME
           Variable used to hard-code SONAME for versioned shared
           library/loadable module.

               env.SharedLibrary('test', 'test.c', SHLIBVERSION='0.1.2', SONAME='libtest.so.2')

           The variable is used, for example, by gnulink linker tool.

       SOURCE
           A reserved variable name that may not be set or used in a
           construction environment. (See "Variable Substitution," below.)

       SOURCE_URL
           The URL (web address) of the location from which the project was
           retrieved. This is used to fill in the Source: field in the
           controlling information for Ipkg and RPM packages.

       SOURCES
           A reserved variable name that may not be set or used in a
           construction environment. (See "Variable Substitution," below.)

       SPAWN
           A command interpreter function that will be called to execute
           command line strings. The function must expect the following
           arguments:

               def spawn(shell, escape, cmd, args, env):


           sh is a string naming the shell program to use.  escape is a
           function that can be called to escape shell special characters in
           the command line.  cmd is the path to the command to be executed.
           args is the arguments to the command.  env is a dictionary of the
           environment variables in which the command should be executed.

       STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME
           When this variable is true, static objects and shared objects are
           assumed to be the same; that is, SCons does not check for linking
           static objects into a shared library.

       SUBST_DICT
           The dictionary used by the Substfile or Textfile builders for
           substitution values. It can be anything acceptable to the dict()
           constructor, so in addition to a dictionary, lists of tuples are
           also acceptable.

       SUBSTFILEPREFIX
           The prefix used for Substfile file names, the null string by
           default.

       SUBSTFILESUFFIX
           The suffix used for Substfile file names, the null string by
           default.

       SUMMARY
           A short summary of what the project is about. This is used to fill
           in the Summary: field in the controlling information for Ipkg and
           RPM packages, and as the Description: field in MSI packages.

       SWIG
           The scripting language wrapper and interface generator.

       SWIGCFILESUFFIX
           The suffix that will be used for intermediate C source files
           generated by the scripting language wrapper and interface
           generator. The default value is _wrap$CFILESUFFIX. By default, this
           value is used whenever the -c++ option is not specified as part of
           the $SWIGFLAGS construction variable.

       SWIGCOM
           The command line used to call the scripting language wrapper and
           interface generator.

       SWIGCOMSTR
           The string displayed when calling the scripting language wrapper
           and interface generator. If this is not set, then $SWIGCOM (the
           command line) is displayed.

       SWIGCXXFILESUFFIX
           The suffix that will be used for intermediate C++ source files
           generated by the scripting language wrapper and interface
           generator. The default value is _wrap$CFILESUFFIX. By default, this
           value is used whenever the -c++ option is specified as part of the
           $SWIGFLAGS construction variable.

       SWIGDIRECTORSUFFIX
           The suffix that will be used for intermediate C++ header files
           generated by the scripting language wrapper and interface
           generator. These are only generated for C++ code when the SWIG
           'directors' feature is turned on. The default value is _wrap.h.

       SWIGFLAGS
           General options passed to the scripting language wrapper and
           interface generator. This is where you should set -python, -perl5,
           -tcl, or whatever other options you want to specify to SWIG. If you
           set the -c++ option in this variable, scons will, by default,
           generate a C++ intermediate source file with the extension that is
           specified as the $CXXFILESUFFIX variable.

       _SWIGINCFLAGS
           An automatically-generated construction variable containing the
           SWIG command-line options for specifying directories to be searched
           for included files. The value of $_SWIGINCFLAGS is created by
           appending $SWIGINCPREFIX and $SWIGINCSUFFIX to the beginning and
           end of each directory in $SWIGPATH.

       SWIGINCPREFIX
           The prefix used to specify an include directory on the SWIG command
           line. This will be appended to the beginning of each directory in
           the $SWIGPATH construction variable when the $_SWIGINCFLAGS
           variable is automatically generated.

       SWIGINCSUFFIX
           The suffix used to specify an include directory on the SWIG command
           line. This will be appended to the end of each directory in the
           $SWIGPATH construction variable when the $_SWIGINCFLAGS variable is
           automatically generated.

       SWIGOUTDIR
           Specifies the output directory in which the scripting language
           wrapper and interface generator should place generated
           language-specific files. This will be used by SCons to identify the
           files that will be generated by the swig call, and translated into
           the swig -outdir option on the command line.

       SWIGPATH
           The list of directories that the scripting language wrapper and
           interface generate will search for included files. The SWIG
           implicit dependency scanner will search these directories for
           include files. The default value is an empty list.

           Don't explicitly put include directory arguments in SWIGFLAGS; the
           result will be non-portable and the directories will not be
           searched by the dependency scanner. Note: directory names in
           SWIGPATH will be looked-up relative to the SConscript directory
           when they are used in a command. To force scons to look-up a
           directory relative to the root of the source tree use #:

               env = Environment(SWIGPATH='#/include')

           The directory look-up can also be forced using the Dir() function:

               include = Dir('include')
               env = Environment(SWIGPATH=include)

           The directory list will be added to command lines through the
           automatically-generated $_SWIGINCFLAGS construction variable, which
           is constructed by appending the values of the $SWIGINCPREFIX and
           $SWIGINCSUFFIX construction variables to the beginning and end of
           each directory in $SWIGPATH. Any command lines you define that need
           the SWIGPATH directory list should include $_SWIGINCFLAGS:

               env = Environment(SWIGCOM="my_swig -o $TARGET $_SWIGINCFLAGS $SOURCES")

       SWIGVERSION
           The version number of the SWIG tool.

       TAR
           The tar archiver.

       TARCOM
           The command line used to call the tar archiver.

       TARCOMSTR
           The string displayed when archiving files using the tar archiver.
           If this is not set, then $TARCOM (the command line) is displayed.

               env = Environment(TARCOMSTR = "Archiving $TARGET")

       TARFLAGS
           General options passed to the tar archiver.

       TARGET
           A reserved variable name that may not be set or used in a
           construction environment. (See "Variable Substitution," below.)

       TARGET_ARCH
           Sets the target architecture for Visual Studio compiler (i.e. the
           arch of the binaries generated by the compiler). If not set,
           default to $HOST_ARCH, or, if that is unset, to the architecture of
           the running machine's OS (note that the python build or
           architecture has no effect). This variable must be passed as an
           argument to the Environment() constructor; setting it later has no
           effect. This is currently only used on Windows, but in the future
           it will be used on other OSes as well.

           Valid values for Windows are x86, i386 (for 32 bits); amd64, emt64,
           x86_64 (for 64 bits); and ia64 (Itanium). For example, if you want
           to compile 64-bit binaries, you would set TARGET_ARCH='x86_64' in
           your SCons environment.

           The name of the target hardware architecture for the compiled
           objects created by this Environment. This defaults to the value of
           HOST_ARCH, and the user can override it. Currently only set for
           Win32.

       TARGET_OS
           The name of the target operating system for the compiled objects
           created by this Environment. This defaults to the value of HOST_OS,
           and the user can override it. Currently only set for Win32.

       TARGETS
           A reserved variable name that may not be set or used in a
           construction environment. (See "Variable Substitution," below.)

       TARSUFFIX
           The suffix used for tar file names.

       TEMPFILEPREFIX
           The prefix for a temporary file used to execute lines longer than
           $MAXLINELENGTH. The default is '@'. This may be set for toolchains
           that use other values, such as '-@' for the diab compiler or '-via'
           for ARM toolchain.

       TEX
           The TeX formatter and typesetter.

       TEXCOM
           The command line used to call the TeX formatter and typesetter.

       TEXCOMSTR
           The string displayed when calling the TeX formatter and typesetter.
           If this is not set, then $TEXCOM (the command line) is displayed.

               env = Environment(TEXCOMSTR = "Building $TARGET from TeX input $SOURCES")

       TEXFLAGS
           General options passed to the TeX formatter and typesetter.

       TEXINPUTS
           List of directories that the LaTeX program will search for include
           directories. The LaTeX implicit dependency scanner will search
           these directories for \include and \import files.

       TEXTFILEPREFIX
           The prefix used for Textfile file names, the null string by
           default.

       TEXTFILESUFFIX
           The suffix used for Textfile file names; .txt by default.

       TOOLS
           A list of the names of the Tool specifications that are part of
           this construction environment.

       UNCHANGED_SOURCES
           A reserved variable name that may not be set or used in a
           construction environment. (See "Variable Substitution," below.)

       UNCHANGED_TARGETS
           A reserved variable name that may not be set or used in a
           construction environment. (See "Variable Substitution," below.)

       VENDOR
           The person or organization who supply the packaged software. This
           is used to fill in the Vendor: field in the controlling information
           for RPM packages, and the Manufacturer: field in the controlling
           information for MSI packages.

       VERSION
           The version of the project, specified as a string.

       WIN32_INSERT_DEF
           A deprecated synonym for $WINDOWS_INSERT_DEF.

       WIN32DEFPREFIX
           A deprecated synonym for $WINDOWSDEFPREFIX.

       WIN32DEFSUFFIX
           A deprecated synonym for $WINDOWSDEFSUFFIX.

       WIN32EXPPREFIX
           A deprecated synonym for $WINDOWSEXPSUFFIX.

       WIN32EXPSUFFIX
           A deprecated synonym for $WINDOWSEXPSUFFIX.

       WINDOWS_EMBED_MANIFEST
           Set this variable to True or 1 to embed the compiler-generated
           manifest (normally ${TARGET}.manifest) into all Windows exes and
           DLLs built with this environment, as a resource during their link
           step. This is done using $MT and $MTEXECOM and $MTSHLIBCOM.

       WINDOWS_INSERT_DEF
           When this is set to true, a library build of a Windows shared
           library (.dll file) will also build a corresponding .def file at
           the same time, if a .def file is not already listed as a build
           target. The default is 0 (do not build a .def file).

       WINDOWS_INSERT_MANIFEST
           When this is set to true, scons will be aware of the .manifest
           files generated by Microsoft Visua C/C++ 8.

       WINDOWSDEFPREFIX
           The prefix used for Windows .def file names.

       WINDOWSDEFSUFFIX
           The suffix used for Windows .def file names.

       WINDOWSEXPPREFIX
           The prefix used for Windows .exp file names.

       WINDOWSEXPSUFFIX
           The suffix used for Windows .exp file names.

       WINDOWSPROGMANIFESTPREFIX
           The prefix used for executable program .manifest files generated by
           Microsoft Visual C/C++.

       WINDOWSPROGMANIFESTSUFFIX
           The suffix used for executable program .manifest files generated by
           Microsoft Visual C/C++.

       WINDOWSSHLIBMANIFESTPREFIX
           The prefix used for shared library .manifest files generated by
           Microsoft Visual C/C++.

       WINDOWSSHLIBMANIFESTSUFFIX
           The suffix used for shared library .manifest files generated by
           Microsoft Visual C/C++.

       X_IPK_DEPENDS
           This is used to fill in the Depends: field in the controlling
           information for Ipkg packages.

       X_IPK_DESCRIPTION
           This is used to fill in the Description: field in the controlling
           information for Ipkg packages. The default value is
           $SUMMARY\n$DESCRIPTION

       X_IPK_MAINTAINER
           This is used to fill in the Maintainer: field in the controlling
           information for Ipkg packages.

       X_IPK_PRIORITY
           This is used to fill in the Priority: field in the controlling
           information for Ipkg packages.

       X_IPK_SECTION
           This is used to fill in the Section: field in the controlling
           information for Ipkg packages.

       X_MSI_LANGUAGE
           This is used to fill in the Language: attribute in the controlling
           information for MSI packages.

       X_MSI_LICENSE_TEXT
           The text of the software license in RTF format. Carriage return
           characters will be replaced with the RTF equivalent \\par.

       X_MSI_UPGRADE_CODE
           TODO

       X_RPM_AUTOREQPROV
           This is used to fill in the AutoReqProv: field in the RPM .spec
           file.

       X_RPM_BUILD
           internal, but overridable

       X_RPM_BUILDREQUIRES
           This is used to fill in the BuildRequires: field in the RPM .spec
           file.

       X_RPM_BUILDROOT
           internal, but overridable

       X_RPM_CLEAN
           internal, but overridable

       X_RPM_CONFLICTS
           This is used to fill in the Conflicts: field in the RPM .spec file.

       X_RPM_DEFATTR
           This value is used as the default attributes for the files in the
           RPM package. The default value is (-,root,root).

       X_RPM_DISTRIBUTION
           This is used to fill in the Distribution: field in the RPM .spec
           file.

       X_RPM_EPOCH
           This is used to fill in the Epoch: field in the controlling
           information for RPM packages.

       X_RPM_EXCLUDEARCH
           This is used to fill in the ExcludeArch: field in the RPM .spec
           file.

       X_RPM_EXLUSIVEARCH
           This is used to fill in the ExclusiveArch: field in the RPM .spec
           file.

       X_RPM_GROUP
           This is used to fill in the Group: field in the RPM .spec file.

       X_RPM_GROUP_lang
           This is used to fill in the Group(lang): field in the RPM .spec
           file. Note that lang is not literal and should be replaced by the
           appropriate language code.

       X_RPM_ICON
           This is used to fill in the Icon: field in the RPM .spec file.

       X_RPM_INSTALL
           internal, but overridable

       X_RPM_PACKAGER
           This is used to fill in the Packager: field in the RPM .spec file.

       X_RPM_POSTINSTALL
           This is used to fill in the %post: section in the RPM .spec file.

       X_RPM_POSTUNINSTALL
           This is used to fill in the %postun: section in the RPM .spec file.

       X_RPM_PREFIX
           This is used to fill in the Prefix: field in the RPM .spec file.

       X_RPM_PREINSTALL
           This is used to fill in the %pre: section in the RPM .spec file.

       X_RPM_PREP
           internal, but overridable

       X_RPM_PREUNINSTALL
           This is used to fill in the %preun: section in the RPM .spec file.

       X_RPM_PROVIDES
           This is used to fill in the Provides: field in the RPM .spec file.

       X_RPM_REQUIRES
           This is used to fill in the Requires: field in the RPM .spec file.

       X_RPM_SERIAL
           This is used to fill in the Serial: field in the RPM .spec file.

       X_RPM_URL
           This is used to fill in the Url: field in the RPM .spec file.

       XGETTEXT
           Path to xgettext(1) program (found via Detect()). See xgettext tool
           and POTUpdate builder.

       XGETTEXTCOM
           Complete xgettext command line. See xgettext tool and POTUpdate
           builder.

       XGETTEXTCOMSTR
           A string that is shown when xgettext(1) command is invoked
           (default: '', which means "print $XGETTEXTCOM"). See xgettext tool
           and POTUpdate builder.

       _XGETTEXTDOMAIN
           Internal "macro". Generates xgettext domain name form source and
           target (default: '${TARGET.filebase}').

       XGETTEXTFLAGS
           Additional flags to xgettext(1). See xgettext tool and POTUpdate
           builder.

       XGETTEXTFROM
           Name of file containing list of xgettext(1)'s source files.
           Autotools' users know this as POTFILES.in so they will in most
           cases set XGETTEXTFROM="POTFILES.in" here. The $XGETTEXTFROM files
           have same syntax and semantics as the well known GNU POTFILES.in.
           See xgettext tool and POTUpdate builder.

       _XGETTEXTFROMFLAGS
           Internal "macro". Genrates list of -D<dir> flags from the
           $XGETTEXTPATH list.

       XGETTEXTFROMPREFIX
           This flag is used to add single $XGETTEXTFROM file to xgettext(1)'s
           commandline (default: '-f').

       XGETTEXTFROMSUFFIX
           (default: '')

       XGETTEXTPATH
           List of directories, there xgettext(1) will look for source files
           (default: []).

               Note
               This variable works only together with $XGETTEXTFROM
           See also xgettext tool and POTUpdate builder.

       _XGETTEXTPATHFLAGS
           Internal "macro". Generates list of -f<file> flags from
           $XGETTEXTFROM.

       XGETTEXTPATHPREFIX
           This flag is used to add single search path to xgettext(1)'s
           commandline (default: '-D').

       XGETTEXTPATHSUFFIX
           (default: '')

       YACC
           The parser generator.

       YACCCOM
           The command line used to call the parser generator to generate a
           source file.

       YACCCOMSTR
           The string displayed when generating a source file using the parser
           generator. If this is not set, then $YACCCOM (the command line) is
           displayed.

               env = Environment(YACCCOMSTR = "Yacc'ing $TARGET from $SOURCES")

       YACCFLAGS
           General options passed to the parser generator. If $YACCFLAGS
           contains a -d option, SCons assumes that the call will also create
           a .h file (if the yacc source file ends in a .y suffix) or a .hpp
           file (if the yacc source file ends in a .yy suffix)

       YACCHFILESUFFIX
           The suffix of the C header file generated by the parser generator
           when the -d option is used. Note that setting this variable does
           not cause the parser generator to generate a header file with the
           specified suffix, it exists to allow you to specify what suffix the
           parser generator will use of its own accord. The default value is
           .h.

       YACCHXXFILESUFFIX
           The suffix of the C++ header file generated by the parser generator
           when the -d option is used. Note that setting this variable does
           not cause the parser generator to generate a header file with the
           specified suffix, it exists to allow you to specify what suffix the
           parser generator will use of its own accord. The default value is
           .hpp, except on Mac OS X, where the default is ${TARGET.suffix}.h.
           because the default bison parser generator just appends .h to the
           name of the generated C++ file.

       YACCVCGFILESUFFIX
           The suffix of the file containing the VCG grammar automaton
           definition when the --graph= option is used. Note that setting this
           variable does not cause the parser generator to generate a VCG file
           with the specified suffix, it exists to allow you to specify what
           suffix the parser generator will use of its own accord. The default
           value is .vcg.

       ZIP
           The zip compression and file packaging utility.

       ZIPCOM
           The command line used to call the zip utility, or the internal
           Python function used to create a zip archive.

       ZIPCOMPRESSION
           The compression flag from the Python zipfile module used by the
           internal Python function to control whether the zip archive is
           compressed or not. The default value is zipfile.ZIP_DEFLATED, which
           creates a compressed zip archive. This value has no effect if the
           zipfile module is unavailable.

       ZIPCOMSTR
           The string displayed when archiving files using the zip utility. If
           this is not set, then $ZIPCOM (the command line or internal Python
           function) is displayed.

               env = Environment(ZIPCOMSTR = "Zipping $TARGET")

       ZIPFLAGS
           General options passed to the zip utility.

       ZIPROOT
           An optional zip root directory (default empty). The filenames
           stored in the zip file will be relative to this directory, if
           given. Otherwise the filenames are relative to the current
           directory of the command. For instance:

               env = Environment()
               env.Zip('foo.zip', 'subdir1/subdir2/file1', ZIPROOT='subdir1')

           will produce a zip file foo.zip containing a file with the name
           subdir2/file1 rather than subdir1/subdir2/file1.

       ZIPSUFFIX
           The suffix used for zip file names.

       Construction variables can be retrieved and set using the Dictionary
       method of the construction environment:

           dict = env.Dictionary()
           dict["CC"] = "cc"

       or using the [] operator:

           env["CC"] = "cc"

       Construction variables can also be passed to the construction
       environment constructor:

           env = Environment(CC="cc")

       or when copying a construction environment using the Clone method:

           env2 = env.Clone(CC="cl.exe")

   Configure Contexts
       scons supports configure contexts, an integrated mechanism similar to
       the various AC_CHECK macros in GNU autoconf for testing for the
       existence of C header files, libraries, etc. In contrast to autoconf,
       scons does not maintain an explicit cache of the tested values, but
       uses its normal dependency tracking to keep the checked values up to
       date. However, users may override this behaviour with the --config
       command line option.

       The following methods can be used to perform checks:

       Configure(env, [custom_tests, conf_dir, log_file, config_h, clean,
       help]), env.Configure([custom_tests, conf_dir, log_file, config_h,
       clean, help])
           This creates a configure context, which can be used to perform
           checks.  env specifies the environment for building the tests. This
           environment may be modified when performing checks.  custom_tests
           is a dictionary containing custom tests. See also the section about
           custom tests below. By default, no custom tests are added to the
           configure context.  conf_dir specifies a directory where the test
           cases are built. Note that this directory is not used for building
           normal targets. The default value is the directory #/.sconf_temp.
           log_file specifies a file which collects the output from commands
           that are executed to check for the existence of header files,
           libraries, etc. The default is the file #/config.log. If you are
           using the VariantDir() method, you may want to specify a
           subdirectory under your variant directory.  config_h specifies a C
           header file where the results of tests will be written, e.g.
           #define HAVE_STDIO_H, #define HAVE_LIBM, etc. The default is to not
           write a config.h file. You can specify the same config.h file in
           multiple calls to Configure, in which case scons will concatenate
           all results in the specified file. Note that SCons uses its normal
           dependency checking to decide if it's necessary to rebuild the
           specified config_h file. This means that the file is not
           necessarily re-built each time scons is run, but is only rebuilt if
           its contents will have changed and some target that depends on the
           config_h file is being built.

           The optional clean and help arguments can be used to suppress
           execution of the configuration tests when the -c/--clean or
           -H/-h/--help options are used, respectively. The default behavior
           is always to execute configure context tests, since the results of
           the tests may affect the list of targets to be cleaned or the help
           text. If the configure tests do not affect these, then you may add
           the clean=False or help=False arguments (or both) to avoid
           unnecessary test execution.

       A created Configure instance has the following associated methods:

       SConf.Finish(context), sconf.Finish()
           This method should be called after configuration is done. It
           returns the environment as modified by the configuration checks
           performed. After this method is called, no further checks can be
           performed with this configuration context. However, you can create
           a new Configure context to perform additional checks. Only one
           context should be active at a time.

           The following Checks are predefined. (This list will likely grow
           larger as time goes by and developers contribute new useful tests.)

       SConf.CheckHeader(context, header, [include_quotes, language]),
       sconf.CheckHeader(header, [include_quotes, language])
           Checks if header is usable in the specified language.  header may
           be a list, in which case the last item in the list is the header
           file to be checked, and the previous list items are header files
           whose #include lines should precede the header line being checked
           for. The optional argument include_quotes must be a two character
           string, where the first character denotes the opening quote and the
           second character denotes the closing quote. By default, both
           characters are " (double quote). The optional argument language
           should be either C or C++ and selects the compiler to be used for
           the check. Returns 1 on success and 0 on failure.

       SConf.CheckCHeader(context, header, [include_quotes]),
       sconf.CheckCHeader(header, [include_quotes])
           This is a wrapper around SConf.CheckHeader which checks if header
           is usable in the C language.  header may be a list, in which case
           the last item in the list is the header file to be checked, and the
           previous list items are header files whose #include lines should
           precede the header line being checked for. The optional argument
           include_quotes must be a two character string, where the first
           character denotes the opening quote and the second character
           denotes the closing quote (both default to \N'34'). Returns 1 on
           success and 0 on failure.

       SConf.CheckCXXHeader(context, header, [include_quotes]),
       sconf.CheckCXXHeader(header, [include_quotes])
           This is a wrapper around SConf.CheckHeader which checks if header
           is usable in the C++ language.  header may be a list, in which case
           the last item in the list is the header file to be checked, and the
           previous list items are header files whose #include lines should
           precede the header line being checked for. The optional argument
           include_quotes must be a two character string, where the first
           character denotes the opening quote and the second character
           denotes the closing quote (both default to \N'34'). Returns 1 on
           success and 0 on failure.

       SConf.CheckFunc(context,, function_name, [header, language]),
       sconf.CheckFunc(function_name, [header, language])
           Checks if the specified C or C++ function is available.
           function_name is the name of the function to check for. The
           optional header argument is a string that will be placed at the top
           of the test file that will be compiled to check if the function
           exists; the default is:

               #ifdef __cplusplus
               extern "C"
               #endif
               char function_name();

           The optional language argument should be C or C++ and selects the
           compiler to be used for the check; the default is "C".

       SConf.CheckLib(context, [library, symbol, header, language,
       autoadd=1]), sconf.CheckLib([library, symbol, header, language,
       autoadd=1])
           Checks if library provides symbol. If the value of autoadd is 1 and
           the library provides the specified symbol, appends the library to
           the LIBS construction environment variable.  library may also be
           None (the default), in which case symbol is checked with the
           current LIBS variable, or a list of library names, in which case
           each library in the list will be checked for symbol. If symbol is
           not set or is None, then SConf.CheckLib() just checks if you can
           link against the specified library. The optional language argument
           should be C or C++ and selects the compiler to be used for the
           check; the default is "C". The default value for autoadd is 1. This
           method returns 1 on success and 0 on error.

       SConf.CheckLibWithHeader(context, library, header, language, [call,
       autoadd]), sconf.CheckLibWithHeader(library, header, language, [call,
       autoadd])
           In contrast to the SConf.CheckLib call, this call provides a more
           sophisticated way to check against libraries. Again, library
           specifies the library or a list of libraries to check.  header
           specifies a header to check for.  header may be a list, in which
           case the last item in the list is the header file to be checked,
           and the previous list items are header files whose #include lines
           should precede the header line being checked for.  language may be
           one of 'C','c','CXX','cxx','C++' and 'c++'.  call can be any valid
           expression (with a trailing ';'). If call is not set, the default
           simply checks that you can link against the specified library.
           autoadd specifies whether to add the library to the environment
           (only if the check succeeds). This method returns 1 on success and
           0 on error.

       SConf.CheckType(context, type_name, [includes, language]),
       sconf.CheckType(type_name, [includes, language])
           Checks for the existence of a type defined by typedef.  type_name
           specifies the typedef name to check for.  includes is a string
           containing one or more #include lines that will be inserted into
           the program that will be run to test for the existence of the type.
           The optional language argument should be C or C++ and selects the
           compiler to be used for the check; the default is "C". Example:

               sconf.CheckType('foo_type', '#include "my_types.h"', 'C++')

       Configure.CheckCC(self)
           Checks whether the C compiler (as defined by the CC construction
           variable) works by trying to compile a small source file.

           By default, SCons only detects if there is a program with the
           correct name, not if it is a functioning compiler.

           This uses the exact same command than the one used by the object
           builder for C source file, so it can be used to detect if a
           particular compiler flag works or not.

       Configure.CheckCXX(self)
           Checks whether the C++ compiler (as defined by the CXX construction
           variable) works by trying to compile a small source file. By
           default, SCons only detects if there is a program with the correct
           name, not if it is a functioning compiler.

           This uses the exact same command than the one used by the object
           builder for CXX source files, so it can be used to detect if a
           particular compiler flag works or not.

       Configure.CheckSHCC(self)
           Checks whether the C compiler (as defined by the SHCC construction
           variable) works by trying to compile a small source file. By
           default, SCons only detects if there is a program with the correct
           name, not if it is a functioning compiler.

           This uses the exact same command than the one used by the object
           builder for C source file, so it can be used to detect if a
           particular compiler flag works or not. This does not check whether
           the object code can be used to build a shared library, only that
           the compilation (not link) succeeds.

       Configure.CheckSHCXX(self)
           Checks whether the C++ compiler (as defined by the SHCXX
           construction variable) works by trying to compile a small source
           file. By default, SCons only detects if there is a program with the
           correct name, not if it is a functioning compiler.

           This uses the exact same command than the one used by the object
           builder for CXX source files, so it can be used to detect if a
           particular compiler flag works or not. This does not check whether
           the object code can be used to build a shared library, only that
           the compilation (not link) succeeds.

       Example of a typical Configure usage:

           env = Environment()
           conf = Configure( env )
           if not conf.CheckCHeader( 'math.h' ):
               print 'We really need math.h!'
               Exit(1)
           if conf.CheckLibWithHeader( 'qt', 'qapp.h', 'c++',
                   'QApplication qapp(0,0);' ):
               # do stuff for qt - usage, e.g.
               conf.env.Append( CPPFLAGS = '-DWITH_QT' )
           env = conf.Finish()

       SConf.CheckTypeSize(context, type_name, [header, language, expect]),
       sconf.CheckTypeSize(type_name, [header, language, expect])
           Checks for the size of a type defined by typedef.  type_name
           specifies the typedef name to check for. The optional header
           argument is a string that will be placed at the top of the test
           file that will be compiled to check if the function exists; the
           default is empty. The optional language argument should be C or C++
           and selects the compiler to be used for the check; the default is
           "C". The optional expect argument should be an integer. If this
           argument is used, the function will only check whether the type
           given in type_name has the expected size (in bytes). For example,
           CheckTypeSize('short', expect = 2) will return success only if
           short is two bytes.


       SConf.CheckDeclaration(context, symbol, [includes, language]),
       sconf.CheckDeclaration(symbol, [includes, language])
           Checks if the specified symbol is declared.  includes is a string
           containing one or more #include lines that will be inserted into
           the program that will be run to test for the existence of the type.
           The optional language argument should be C or C++ and selects the
           compiler to be used for the check; the default is "C".

       SConf.Define(context, symbol, [value, comment]), sconf.Define(symbol,
       [value, comment])
           This function does not check for anything, but defines a
           preprocessor symbol that will be added to the configuration header
           file. It is the equivalent of AC_DEFINE, and defines the symbol
           name with the optional value and the optional comment comment.

       Examples:

           env = Environment()
           conf = Configure( env )

           # Puts the following line in the config header file:
           #    #define A_SYMBOL
           conf.Define('A_SYMBOL')

           # Puts the following line in the config header file:
           #    #define A_SYMBOL 1
           conf.Define('A_SYMBOL', 1)

       Be careful about quoting string values, though:

           env = Environment()
           conf = Configure( env )

           # Puts the following line in the config header file:
           #    #define A_SYMBOL YA
           conf.Define('A_SYMBOL', "YA")

           # Puts the following line in the config header file:
           #    #define A_SYMBOL "YA"
           conf.Define('A_SYMBOL', '"YA"')

       For comment:

           env = Environment()
           conf = Configure( env )

           # Puts the following lines in the config header file:
           #    /* Set to 1 if you have a symbol */
           #    #define A_SYMBOL 1
           conf.Define('A_SYMBOL', 1, 'Set to 1 if you have a symbol')

       You can define your own custom checks. in addition to the predefined
       checks. These are passed in a dictionary to the Configure function.
       This dictionary maps the names of the checks to user defined Python
       callables (either Python functions or class instances implementing the
       __call__ method). The first argument of the call is always a
       CheckContext instance followed by the arguments, which must be supplied
       by the user of the check. These CheckContext instances define the
       following methods:

       CheckContext.Message(self, text)
           Usually called before the check is started.  text will be displayed
           to the user, e.g. 'Checking for library X...'

       CheckContext.Result(self,, res)
           Usually called after the check is done.  res can be either an
           integer or a string. In the former case, 'yes' (res != 0) or 'no'
           (res == 0) is displayed to the user, in the latter case the given
           string is displayed.

       CheckContext.TryCompile(self, text, extension)
           Checks if a file with the specified extension (e.g. '.c')
           containing text can be compiled using the environment's Object
           builder. Returns 1 on success and 0 on failure.

       CheckContext.TryLink(self, text, extension)
           Checks, if a file with the specified extension (e.g. '.c')
           containing text can be compiled using the environment's Program
           builder. Returns 1 on success and 0 on failure.

       CheckContext.TryRun(self, text, extension)
           Checks, if a file with the specified extension (e.g. '.c')
           containing text can be compiled using the environment's Program
           builder. On success, the program is run. If the program executes
           successfully (that is, its return status is 0), a tuple (1,
           outputStr) is returned, where outputStr is the standard output of
           the program. If the program fails execution (its return status is
           non-zero), then (0, '') is returned.

       CheckContext.TryAction(self, action, [text, extension])
           Checks if the specified action with an optional source file
           (contents text , extension extension = '' ) can be executed.
           action may be anything which can be converted to a scons Action. On
           success, (1, outputStr) is returned, where outputStr is the content
           of the target file. On failure (0, '') is returned.

       CheckContext.TryBuild(self, builder, [text, extension])
           Low level implementation for testing specific builds; the methods
           above are based on this method. Given the Builder instance builder
           and the optional text of a source file with optional extension,
           this method returns 1 on success and 0 on failure. In addition,
           self.lastTarget is set to the build target node, if the build was
           successful.

       Example for implementing and using custom tests:

           def CheckQt(context, qtdir):
               context.Message( 'Checking for qt ...' )
               lastLIBS = context.env['LIBS']
               lastLIBPATH = context.env['LIBPATH']
               lastCPPPATH= context.env['CPPPATH']
               context.env.Append(LIBS = 'qt', LIBPATH = qtdir + '/lib', CPPPATH = qtdir + '/include' )
               ret = context.TryLink("""
           #include <qapp.h>
           int main(int argc, char **argv) {
             QApplication qapp(argc, argv);
             return 0;
           }
           """)
               if not ret:
                   context.env.Replace(LIBS = lastLIBS, LIBPATH=lastLIBPATH, CPPPATH=lastCPPPATH)
               context.Result( ret )
               return ret

           env = Environment()
           conf = Configure( env, custom_tests = { 'CheckQt' : CheckQt } )
           if not conf.CheckQt('/usr/lib/qt'):
               print 'We really need qt!'
               Exit(1)
           env = conf.Finish()

   Command-Line Construction Variables
       Often when building software, some variables must be specified at build
       time. For example, libraries needed for the build may be in
       non-standard locations, or site-specific compiler options may need to
       be passed to the compiler.  scons provides a Variables object to
       support overriding construction variables on the command line:

           $ scons VARIABLE=foo

       The variable values can also be specified in a text-based SConscript
       file. To create a Variables object, call the Variables() function:

       Variables([files], [args])
           This creates a Variables object that will read construction
           variables from the file or list of filenames specified in files. If
           no files are specified, or the files argument is None, then no
           files will be read. The optional argument args is a dictionary of
           values that will override anything read from the specified files;
           it is primarily intended to be passed the ARGUMENTS dictionary that
           holds variables specified on the command line. Example:

               vars = Variables('custom.py')
               vars = Variables('overrides.py', ARGUMENTS)
               vars = Variables(None, {FOO:'expansion', BAR:7})

           Variables objects have the following methods:

       Add(key, [help, default, validator, converter])
           This adds a customizable construction variable to the Variables
           object.  key is the name of the variable.  help is the help text
           for the variable.  default is the default value of the variable; if
           the default value is None and there is no explicit value specified,
           the construction variable will not be added to the construction
           environment.  validator is called to validate the value of the
           variable, and should take three arguments: key, value, and
           environment. The recommended way to handle an invalid value is to
           raise an exception (see example below).  converter is called to
           convert the value before putting it in the environment, and should
           take either a value, or the value and environment, as parameters.
           The converter must return a value, which will be converted into a
           string before being validated by the validator (if any) and then
           added to the environment.

           Examples:

               vars.Add('CC', 'The C compiler')

               def validate_color(key, val, env):
                   if not val in ['red', 'blue', 'yellow']:
                       raise Exception("Invalid color value '%s'" % val)
               vars.Add('COLOR', validator=valid_color)

       AddVariables(list)
           A wrapper script that adds multiple customizable construction
           variables to a Variables object.  list is a list of tuple or list
           objects that contain the arguments for an individual call to the
           Add method.

               opt.AddVariables(
                      ('debug', '', 0),
                      ('CC', 'The C compiler'),
                      ('VALIDATE', 'An option for testing validation',
                       'notset', validator, None),
                   )

       Update(env, [args])
           This updates a construction environment env with the customized
           construction variables. Any specified variables that are not
           configured for the Variables object will be saved and may be
           retrieved with the UnknownVariables() method, below.

           Normally this method is not called directly, but is called
           indirectly by passing the Variables object to the Environment()
           function:

               env = Environment(variables=vars)

       The text file(s) that were specified when the Variables object was
       created are executed as Python scripts, and the values of (global)
       Python variables set in the file are added to the construction
       environment.

       Example:

           CC = 'my_cc'

       UnknownVariables()
           Returns a dictionary containing any variables that were specified
           either in the files or the dictionary with which the Variables
           object was initialized, but for which the Variables object was not
           configured.

               env = Environment(variables=vars)
               for key, value in vars.UnknownVariables():
                   print "unknown variable:  %s=%s" % (key, value)

       Save(filename, env)
           This saves the currently set variables into a script file named
           filename that can be used on the next invocation to automatically
           load the current settings. This method combined with the Variables
           method can be used to support caching of variables between runs.

               env = Environment()
               vars = Variables(['variables.cache', 'custom.py'])
               vars.Add(...)
               vars.Update(env)
               vars.Save('variables.cache', env)

       GenerateHelpText(env, [sort])
           This generates help text documenting the customizable construction
           variables suitable to passing in to the Help() function.  env is
           the construction environment that will be used to get the actual
           values of customizable variables. Calling with an optional sort
           function will cause the output to be sorted by the specified
           argument. The specific sort function should take two arguments and
           return -1, 0 or 1 (like the standard Python cmp function).

               Help(vars.GenerateHelpText(env))
               Help(vars.GenerateHelpText(env, sort=cmp))

       FormatVariableHelpText(env, opt, help, default, actual)
           This method returns a formatted string containing the printable
           help text for one option. It is normally not called directly, but
           is called by the GenerateHelpText() method to create the returned
           help text. It may be overridden with your own function that takes
           the arguments specified above and returns a string of help text
           formatted to your liking. Note that the GenerateHelpText() will not
           put any blank lines or extra characters in between the entries, so
           you must add those characters to the returned string if you want
           the entries separated.

               def my_format(env, opt, help, default, actual):
                   fmt = "\n%s: default=%s actual=%s (%s)\n"
                   return fmt % (opt, default. actual, help)
               vars.FormatVariableHelpText = my_format

           To make it more convenient to work with customizable Variables,
           scons provides a number of functions that make it easy to set up
           various types of Variables:

       BoolVariable(key, help, default)
           Return a tuple of arguments to set up a Boolean option. The option
           will use the specified name key, have a default value of default,
           and display the specified help text. The option will interpret the
           values y, yes, t, true, 1, on and all as true, and the values n,
           no, f, false, 0, off and none as false.

       EnumVariable(key, help, default, allowed_values, [map, ignorecase])
           Return a tuple of arguments to set up an option whose value may be
           one of a specified list of legal enumerated values. The option will
           use the specified name key, have a default value of default, and
           display the specified help text. The option will only support those
           values in the allowed_values list. The optional map argument is a
           dictionary that can be used to convert input values into specific
           legal values in the allowed_values list. If the value of
           ignore_case is 0 (the default), then the values are case-sensitive.
           If the value of ignore_case is 1, then values will be matched
           case-insensitive. If the value of ignore_case is 2, then values
           will be matched case-insensitive, and all input values will be
           converted to lower case.

       ListVariable(key, help, default, names, [,map])
           Return a tuple of arguments to set up an option whose value may be
           one or more of a specified list of legal enumerated values. The
           option will use the specified name key, have a default value of
           default, and display the specified help text. The option will only
           support the values all, none, or the values in the names list. More
           than one value may be specified, with all values separated by
           commas. The default may be a string of comma-separated default
           values, or a list of the default values. The optional map argument
           is a dictionary that can be used to convert input values into
           specific legal values in the names list.

       PackageVariable(key, help, default)
           Return a tuple of arguments to set up an option whose value is a
           path name of a package that may be enabled, disabled or given an
           explicit path name. The option will use the specified name key,
           have a default value of default, and display the specified help
           text. The option will support the values yes, true, on, enable or
           search, in which case the specified default will be used, or the
           option may be set to an arbitrary string (typically the path name
           to a package that is being enabled). The option will also support
           the values no, false, off or disable to disable use of the
           specified option.

       PathVariable(key, help, default, [validator])
           Return a tuple of arguments to set up an option whose value is
           expected to be a path name. The option will use the specified name
           key, have a default value of default, and display the specified
           help text. An additional validator may be specified that will be
           called to verify that the specified path is acceptable. SCons
           supplies the following ready-made validators:
           PathVariable.PathExists (the default), which verifies that the
           specified path exists; PathVariable.PathIsFile, which verifies that
           the specified path is an existing file; PathVariable.PathIsDir,
           which verifies that the specified path is an existing directory;
           PathVariable.PathIsDirCreate, which verifies that the specified
           path is a directory and will create the specified directory if the
           path does not exist; and PathVariable.PathAccept, which simply
           accepts the specific path name argument without validation, and
           which is suitable if you want your users to be able to specify a
           directory path that will be created as part of the build process,
           for example. You may supply your own validator function, which must
           take three arguments (key, the name of the variable to be set; val,
           the specified value being checked; and env, the construction
           environment) and should raise an exception if the specified value
           is not acceptable.

       These functions make it convenient to create a number of variables with
       consistent behavior in a single call to the AddVariables method:

           vars.AddVariables(
               BoolVariable('warnings', 'compilation with -Wall and similiar', 1),
               EnumVariable('debug', 'debug output and symbols', 'no'
                          allowed_values=('yes', 'no', 'full'),
                          map={}, ignorecase=0),  # case sensitive
               ListVariable('shared',
                          'libraries to build as shared libraries',
                          'all',
                          names = list_of_libs),
               PackageVariable('x11',
                             'use X11 installed here (yes = search some places)',
                             'yes'),
               PathVariable('qtdir', 'where the root of Qt is installed', qtdir),
               PathVariable('foopath', 'where the foo library is installed', foopath,
                          PathVariable.PathIsDir),

           )

   File and Directory Nodes
       The File() and Dir() functions return File and Dir Nodes, respectively.
       python objects, respectively. Those objects have several user-visible
       attributes and methods that are often useful:

       path
           The build path of the given file or directory. This path is
           relative to the top-level directory (where the SConstruct file is
           found). The build path is the same as the source path if
           variant_dir is not being used.

       abspath
           The absolute build path of the given file or directory.

       srcnode()
           The srcnode() method returns another File or Dir object
           representing the source path of the given File or Dir. The

               # Get the current build dir's path, relative to top.
               Dir('.').path
               # Current dir's absolute path
               Dir('.').abspath
               # Next line is always '.', because it is the top dir's path relative to itself.
               Dir('#.').path
               File('foo.c').srcnode().path   # source path of the given source file.

               # Builders also return File objects:
               foo = env.Program('foo.c')
               print "foo will be built in %s"%foo.path

           A Dir Node or File Node can also be used to create file and
           subdirectory Nodes relative to the generating Node. A Dir Node will
           place the new Nodes within the directory it represents. A File node
           will place the new Nodes within its parent directory (that is,
           "beside" the file in question). If d is a Dir (directory) Node and
           f is a File (file) Node, then these methods are available:

       d.Dir(name)
           Returns a directory Node for a subdirectory of d named name.

       d.File(name)
           Returns a file Node for a file within d named name.

       d.Entry(name)
           Returns an unresolved Node within d named name.

       f.Dir(name)
           Returns a directory named name within the parent directory of f.

       f.File(name)
           Returns a file named name within the parent directory of f.

       f.Entry(name)
           Returns an unresolved Node named name within the parent directory
           of f.

       For example:

           # Get a Node for a file within a directory
           incl = Dir('include')
           f = incl.File('header.h')

           # Get a Node for a subdirectory within a directory
           dist = Dir('project-3.2.1)
           src = dist.Dir('src')

           # Get a Node for a file in the same directory
           cfile = File('sample.c')
           hfile = cfile.File('sample.h')

           # Combined example
           docs = Dir('docs')
           html = docs.Dir('html')
           index = html.File('index.html')
           css = index.File('app.css')

EXTENDING SCONS
   Builder Objects
       scons can be extended to build different types of targets by adding new
       Builder objects to a construction environment.  In general, you should
       only need to add a new Builder object when you want to build a new type
       of file or other external target. If you just want to invoke a
       different compiler or other tool to build a Program, Object, Library,
       or any other type of output file for which scons already has an
       existing Builder, it is generally much easier to use those existing
       Builders in a construction environment that sets the appropriate
       construction variables (CC, LINK, etc.).

       Builder objects are created using the Builder function. The Builder
       function accepts the following arguments:

       action
           The command line string used to build the target from the source.
           action can also be: a list of strings representing the command to
           be executed and its arguments (suitable for enclosing white space
           in an argument), a dictionary mapping source file name suffixes to
           any combination of command line strings (if the builder should
           accept multiple source file extensions), a Python function; an
           Action object (see the next section); or a list of any of the
           above.

           An action function takes three arguments: source - a list of source
           nodes, target - a list of target nodes, env - the construction
           environment.

       prefix
           The prefix that will be prepended to the target file name. This may
           be specified as a: * string,

           * callable object - a function or other callable that takes two
           arguments (a construction environment and a list of sources) and
           returns a prefix,

           * dictionary - specifies a mapping from a specific source suffix
           (of the first source specified) to a corresponding target prefix.
           Both the source suffix and target prefix specifications may use
           environment variable substitution, and the target prefix (the
           'value' entries in the dictionary) may also be a callable object.
           The default target prefix may be indicated by a dictionary entry
           with a key value of None.

           b = Builder("build_it < $SOURCE > $TARGET",
                       prefix = "file-")

           def gen_prefix(env, sources):
               return "file-" + env['PLATFORM'] + '-'
           b = Builder("build_it < $SOURCE > $TARGET",
                       prefix = gen_prefix)

           b = Builder("build_it < $SOURCE > $TARGET",
                       suffix = { None: "file-",
                                  "$SRC_SFX_A": gen_prefix })

       suffix
           The suffix that will be appended to the target file name. This may
           be specified in the same manner as the prefix above. If the suffix
           is a string, then scons will append a '.' to the beginning of the
           suffix if it's not already there. The string returned by callable
           object (or obtained from the dictionary) is untouched and must
           append its own '.' to the beginning if one is desired.

               b = Builder("build_it < $SOURCE > $TARGET"
                           suffix = "-file")

               def gen_suffix(env, sources):
                   return "." + env['PLATFORM'] + "-file"
               b = Builder("build_it < $SOURCE > $TARGET",
                           suffix = gen_suffix)

               b = Builder("build_it < $SOURCE > $TARGET",
                           suffix = { None: ".sfx1",
                                      "$SRC_SFX_A": gen_suffix })

       ensure_suffix
           When set to any true value, causes scons to add the target suffix
           specified by the suffix keyword to any target strings that have a
           different suffix. (The default behavior is to leave untouched any
           target file name that looks like it already has any suffix.)

               b1 = Builder("build_it < $SOURCE > $TARGET"
                            suffix = ".out")
               b2 = Builder("build_it < $SOURCE > $TARGET"
                            suffix = ".out",
                            ensure_suffix)
               env = Environment()
               env['BUILDERS']['B1'] = b1
               env['BUILDERS']['B2'] = b2

               # Builds "foo.txt" because ensure_suffix is not set.
               env.B1('foo.txt', 'foo.in')

               # Builds "bar.txt.out" because ensure_suffix is set.
               env.B2('bar.txt', 'bar.in')

       src_suffix
           The expected source file name suffix. This may be a string or a
           list of strings.

       target_scanner
           A Scanner object that will be invoked to find implicit dependencies
           for this target file. This keyword argument should be used for
           Scanner objects that find implicit dependencies based only on the
           target file and the construction environment, not for implicit
           dependencies based on source files. (See the section "Scanner
           Objects" below, for information about creating Scanner objects.)

       source_scanner
           A Scanner object that will be invoked to find implicit dependencies
           in any source files used to build this target file. This is where
           you would specify a scanner to find things like #include lines in
           source files. The pre-built DirScanner Scanner object may be used
           to indicate that this Builder should scan directory trees for
           on-disk changes to files that scons does not know about from other
           Builder or function calls. (See the section "Scanner Objects"
           below, for information about creating your own Scanner objects.)

       target_factory
           A factory function that the Builder will use to turn any targets
           specified as strings into SCons Nodes. By default, SCons assumes
           that all targets are files. Other useful target_factory values
           include Dir, for when a Builder creates a directory target, and
           Entry, for when a Builder can create either a file or directory
           target.

           Example:

               MakeDirectoryBuilder = Builder(action=my_mkdir, target_factory=Dir)
               env = Environment()
               env.Append(BUILDERS = {'MakeDirectory':MakeDirectoryBuilder})
               env.MakeDirectory('new_directory', [])

           Note that the call to the MakeDirectory Builder needs to specify an
           empty source list to make the string represent the builder's
           target; without that, it would assume the argument is the source,
           and would try to deduce the target name from it, which in the
           absence of an automatically-added prefix or suffix would lead to a
           matching target and source name and a circular dependency.

       source_factory
           A factory function that the Builder will use to turn any sources
           specified as strings into SCons Nodes. By default, SCons assumes
           that all source are files. Other useful source_factory values
           include Dir, for when a Builder uses a directory as a source, and
           Entry, for when a Builder can use files or directories (or both) as
           sources.

           Example:

               CollectBuilder = Builder(action=my_mkdir, source_factory=Entry)
               env = Environment()
               env.Append(BUILDERS = {'Collect':CollectBuilder})
               env.Collect('archive', ['directory_name', 'file_name'])

       emitter
           A function or list of functions to manipulate the target and source
           lists before dependencies are established and the target(s) are
           actually built.  emitter can also be a string containing a
           construction variable to expand to an emitter function or list of
           functions, or a dictionary mapping source file suffixes to emitter
           functions. (Only the suffix of the first source file is used to
           select the actual emitter function from an emitter dictionary.)

           An emitter function takes three arguments: source - a list of
           source nodes, target - a list of target nodes, env - the
           construction environment. An emitter must return a tuple containing
           two lists, the list of targets to be built by this builder, and the
           list of sources for this builder.

           Example:

               def e(target, source, env):
                   return (target + ['foo.foo'], source + ['foo.src'])

               # Simple association of an emitter function with a Builder.
               b = Builder("my_build < $TARGET > $SOURCE",
                           emitter = e)

               def e2(target, source, env):
                   return (target + ['bar.foo'], source + ['bar.src'])

               # Simple association of a list of emitter functions with a Builder.
               b = Builder("my_build < $TARGET > $SOURCE",
                           emitter = [e, e2])

               # Calling an emitter function through a construction variable.
               env = Environment(MY_EMITTER = e)
               b = Builder("my_build < $TARGET > $SOURCE",
                           emitter = '$MY_EMITTER')

               # Calling a list of emitter functions through a construction variable.
               env = Environment(EMITTER_LIST = [e, e2])
               b = Builder("my_build < $TARGET > $SOURCE",
                           emitter = '$EMITTER_LIST')

               # Associating multiple emitters with different file
               # suffixes using a dictionary.
               def e_suf1(target, source, env):
                   return (target + ['another_target_file'], source)
               def e_suf2(target, source, env):
                   return (target, source + ['another_source_file'])
               b = Builder("my_build < $TARGET > $SOURCE",
                           emitter = {'.suf1' : e_suf1,
                                      '.suf2' : e_suf2})

       multi
           Specifies whether this builder is allowed to be called multiple
           times for the same target file(s). The default is 0, which means
           the builder can not be called multiple times for the same target
           file(s). Calling a builder multiple times for the same target
           simply adds additional source files to the target; it is not
           allowed to change the environment associated with the target,
           specify addition environment overrides, or associate a different
           builder with the target.

       env
           A construction environment that can be used to fetch source code
           using this Builder. (Note that this environment is not used for
           normal builds of normal target files, which use the environment
           that was used to call the Builder for the target file.)

       generator
           A function that returns a list of actions that will be executed to
           build the target(s) from the source(s). The returned action(s) may
           be an Action object, or anything that can be converted into an
           Action object (see the next section).

           The generator function takes four arguments: source - a list of
           source nodes, target - a list of target nodes, env - the
           construction environment, for_signature - a Boolean value that
           specifies whether the generator is being called for generating a
           build signature (as opposed to actually executing the command).
           Example:

               def g(source, target, env, for_signature):
                   return [["gcc", "-c", "-o"] + target + source]

               b = Builder(generator=g)

           The generator and action arguments must not both be used for the
           same Builder.

       src_builder
           Specifies a builder to use when a source file name suffix does not
           match any of the suffixes of the builder. Using this argument
           produces a multi-stage builder.

       single_source
           Specifies that this builder expects exactly one source file per
           call. Giving more than one source file without target files results
           in implicitly calling the builder multiple times (once for each
           source given). Giving multiple source files together with target
           files results in a UserError exception.

       The generator and action arguments must not both be used for the same
       Builder.

       source_ext_match
           When the specified action argument is a dictionary, the default
           behavior when a builder is passed multiple source files is to make
           sure that the extensions of all the source files match. If it is
           legal for this builder to be called with a list of source files
           with different extensions, this check can be suppressed by setting
           source_ext_match to None or some other non-true value. When
           source_ext_match is disable, scons will use the suffix of the first
           specified source file to select the appropriate action from the
           action dictionary.

           In the following example, the setting of source_ext_match prevents
           scons from exiting with an error due to the mismatched suffixes of
           foo.in and foo.extra.

               b = Builder(action={'.in' : 'build $SOURCES > $TARGET'},
                           source_ext_match = None)

               env = Environment(BUILDERS = {'MyBuild':b})
               env.MyBuild('foo.out', ['foo.in', 'foo.extra'])

       env
           A construction environment that can be used to fetch source code
           using this Builder. (Note that this environment is not used for
           normal builds of normal target files, which use the environment
           that was used to call the Builder for the target file.)

               b = Builder(action="build < $SOURCE > $TARGET")
               env = Environment(BUILDERS = {'MyBuild' : b})
               env.MyBuild('foo.out', 'foo.in', my_arg = 'xyzzy')

       chdir
           A directory from which scons will execute the action(s) specified
           for this Builder. If the chdir argument is a string or a directory
           Node, scons will change to the specified directory. If the chdir is
           not a string or Node and is non-zero, then scons will change to the
           target file's directory.

           Note that scons will not automatically modify its expansion of
           construction variables like $TARGET and $SOURCE when using the
           chdir keyword argument--that is, the expanded file names will still
           be relative to the top-level SConstruct directory, and consequently
           incorrect relative to the chdir directory. Builders created using
           chdir keyword argument, will need to use construction variable
           expansions like ${TARGET.file} and ${SOURCE.file} to use just the
           filename portion of the targets and source.

               b = Builder(action="build < ${SOURCE.file} > ${TARGET.file}",
                           chdir=1)
               env = Environment(BUILDERS = {'MyBuild' : b})
               env.MyBuild('sub/dir/foo.out', 'sub/dir/foo.in')

           WARNING: Python only keeps one current directory location for all
           of the threads. This means that use of the chdir argument will not
           work with the SCons -j option, because individual worker threads
           spawned by SCons interfere with each other when they start changing
           directory.

       Any additional keyword arguments supplied when a Builder object is
       created (that is, when the Builder() function is called) will be set in
       the executing construction environment when the Builder object is
       called. The canonical example here would be to set a construction
       variable to the repository of a source code system.

       Any additional keyword arguments supplied when a Builder object is
       called will only be associated with the target created by that
       particular Builder call (and any other files built as a result of the
       call).

       These extra keyword arguments are passed to the following functions:
       command generator functions, function Actions, and emitter functions.

   Action Objects
       The Builder() function will turn its action keyword argument into an
       appropriate internal Action object. You can also explicitly create
       Action objects using the Action() global function, which can then be
       passed to the Builder() function. This can be used to configure an
       Action object more flexibly, or it may simply be more efficient than
       letting each separate Builder object create a separate Action when
       multiple Builder objects need to do the same thing.

       The Action() global function returns an appropriate object for the
       action represented by the type of the first argument:

       Action
           If the first argument is already an Action object, the object is
           simply returned.

       String
           If the first argument is a string, a command-line Action is
           returned. Note that the command-line string may be preceded by an @
           (at-sign) to suppress printing of the specified command line, or by
           a - (hyphen) to ignore the exit status from the specified command:

               Action('$CC -c -o $TARGET $SOURCES')

               # Doesn't print the line being executed.
               Action('@build $TARGET $SOURCES')

               # Ignores return value
               Action('-build $TARGET $SOURCES')

       List
           If the first argument is a list, then a list of Action objects is
           returned. An Action object is created as necessary for each element
           in the list. If an element within the list is itself a list, the
           internal list is the command and arguments to be executed via the
           command line. This allows white space to be enclosed in an argument
           by defining a command in a list within a list:

               Action([['cc', '-c', '-DWHITE SPACE', '-o', '$TARGET', '$SOURCES']])

       Function
           If the first argument is a Python function, a function Action is
           returned. The Python function must take three keyword arguments,
           target (a Node object representing the target file), source (a Node
           object representing the source file) and env (the construction
           environment used for building the target file). The target and
           source arguments may be lists of Node objects if there is more than
           one target file or source file. The actual target and source file
           name(s) may be retrieved from their Node objects via the built-in
           Python str() function:

               target_file_name = str(target)
               source_file_names = map(lambda x: str(x), source)

           The function should return 0 or None to indicate a successful build
           of the target file(s). The function may raise an exception or
           return a non-zero exit status to indicate an unsuccessful build.

               def build_it(target = None, source = None, env = None):
                   # build the target from the source
                   return 0

               a = Action(build_it)

           If the action argument is not one of the above, None is returned.

       The second argument is optional and is used to define the output which
       is printed when the Action is actually performed. In the absence of
       this parameter, or if it's an empty string, a default output depending
       on the type of the action is used. For example, a command-line action
       will print the executed command. The argument must be either a Python
       function or a string.

       In the first case, it's a function that returns a string to be printed
       to describe the action being executed. The function may also be
       specified by the strfunction= keyword argument. Like a function to
       build a file, this function must take three keyword arguments: target
       (a Node object representing the target file), source (a Node object
       representing the source file) and env (a construction environment). The
       target and source arguments may be lists of Node objects if there is
       more than one target file or source file.

       In the second case, you provide the string itself. The string may also
       be specified by the cmdstr= keyword argument. The string typically
       contains variables, notably $TARGET(S) and $SOURCE(S), or consists of
       just a single variable, which is optionally defined somewhere else.
       SCons itself heavily uses the latter variant.

       Examples:

           def build_it(target, source, env):
               # build the target from the source
               return 0

           def string_it(target, source, env):
               return "building '%s' from '%s'" % (target[0], source[0])

           # Use a positional argument.
           f = Action(build_it, string_it)
           s = Action(build_it, "building '$TARGET' from '$SOURCE'")

           # Alternatively, use a keyword argument.
           f = Action(build_it, strfunction=string_it)
           s = Action(build_it, cmdstr="building '$TARGET' from '$SOURCE'")

           # You can provide a configurable variable.
           l = Action(build_it, '$STRINGIT')

       The third and succeeding arguments, if present, may either be a
       construction variable or a list of construction variables whose values
       will be included in the signature of the Action when deciding whether a
       target should be rebuilt because the action changed. The variables may
       also be specified by a varlist= keyword parameter; if both are present,
       they are combined. This is necessary whenever you want a target to be
       rebuilt when a specific construction variable changes. This is not
       often needed for a string action, as the expanded variables will
       normally be part of the command line, but may be needed if a Python
       function action uses the value of a construction variable when
       generating the command line.

           def build_it(target, source, env):
               # build the target from the 'XXX' construction variable
               open(target[0], 'w').write(env['XXX'])
               return 0

           # Use positional arguments.
           a = Action(build_it, '$STRINGIT', ['XXX'])

           # Alternatively, use a keyword argument.
           a = Action(build_it, varlist=['XXX'])

       The Action() global function can be passed the following optional
       keyword arguments to modify the Action object's behavior:

       chdir The chdir keyword argument specifies that scons will execute the
       action after changing to the specified directory. If the chdir argument
       is a string or a directory Node, scons will change to the specified
       directory. If the chdir argument is not a string or Node and is
       non-zero, then scons will change to the target file's directory.

       Note that scons will not automatically modify its expansion of
       construction variables like $TARGET and $SOURCE when using the chdir
       keyword argument--that is, the expanded file names will still be
       relative to the top-level SConstruct directory, and consequently
       incorrect relative to the chdir directory. Builders created using chdir
       keyword argument, will need to use construction variable expansions
       like ${TARGET.file} and ${SOURCE.file} to use just the filename portion
       of the targets and source.

           a = Action("build < ${SOURCE.file} > ${TARGET.file}",
                      chdir=1)

       exitstatfunc The Action() global function also takes an exitstatfunc
       keyword argument which specifies a function that is passed the exit
       status (or return value) from the specified action and can return an
       arbitrary or modified value. This can be used, for example, to specify
       that an Action object's return value should be ignored under special
       conditions and SCons should, therefore, consider that the action always
       suceeds:

           def always_succeed(s):
               # Always return 0, which indicates success.
               return 0
           a = Action("build < ${SOURCE.file} > ${TARGET.file}",
                      exitstatfunc=always_succeed)

       batch_key The batch_key keyword argument can be used to specify that
       the Action can create multiple target files by processing multiple
       independent source files simultaneously. (The canonical example is
       "batch compilation" of multiple object files by passing multiple source
       files to a single invocation of a compiler such as Microsoft's Visual C
       / C++ compiler.) If the batch_key argument is any non-False,
       non-callable Python value, the configured Action object will cause
       scons to collect all targets built with the Action object and
       configured with the same construction environment into single
       invocations of the Action object's command line or function. Command
       lines will typically want to use the CHANGED_SOURCES construction
       variable (and possibly CHANGED_TARGETS as well) to only pass to the
       command line those sources that have actually changed since their
       targets were built.

       Example:

           a = Action('build $CHANGED_SOURCES', batch_key=True)

       The batch_key argument may also be a callable function that returns a
       key that will be used to identify different "batches" of target files
       to be collected for batch building. A batch_key function must take the
       following arguments:

       action
           The action object.

       env
           The construction environment configured for the target.

       target
           The list of targets for a particular configured action.

       source
           The list of source for a particular configured action.

           The returned key should typically be a tuple of values derived from
           the arguments, using any appropriate logic to decide how multiple
           invocations should be batched. For example, a batch_key function
           may decide to return the value of a specific construction variable
           from the env argument which will cause scons to batch-build targets
           with matching values of that variable, or perhaps return the id()
           of the entire construction environment, in which case scons will
           batch-build all targets configured with the same construction
           environment. Returning None indicates that the particular target
           should not be part of any batched build, but instead will be built
           by a separate invocation of action's command or function. Example:

               def batch_key(action, env, target, source):
                   tdir = target[0].dir
                   if tdir.name == 'special':
                       # Don't batch-build any target
                       # in the special/ subdirectory.
                       return None
                   return (id(action), id(env), tdir)
               a = Action('build $CHANGED_SOURCES', batch_key=batch_key)

   Miscellaneous Action Functions
       scons supplies a number of functions that arrange for various common
       file and directory manipulations to be performed. These are similar in
       concept to "tasks" in the Ant build tool, although the implementation
       is slightly different. These functions do not actually perform the
       specified action at the time the function is called, but instead return
       an Action object that can be executed at the appropriate time. (In
       Object-Oriented terminology, these are actually Action Factory
       functions that return Action objects.)

       In practice, there are two natural ways that these Action Functions are
       intended to be used.

       First, if you need to perform the action at the time the SConscript
       file is being read, you can use the Execute global function to do so:

           Execute(Touch('file'))

       Second, you can use these functions to supply Actions in a list for use
       by the Command method. This can allow you to perform more complicated
       sequences of file manipulation without relying on platform-specific
       external commands: that

           env = Environment(TMPBUILD = '/tmp/builddir')
           env.Command('foo.out', 'foo.in',
                       [Mkdir('$TMPBUILD'),
                        Copy('$TMPBUILD', '${SOURCE.dir}'),
                        "cd $TMPBUILD && make",
                        Delete('$TMPBUILD')])

       Chmod(dest, mode)
           Returns an Action object that changes the permissions on the
           specified dest file or directory to the specified mode which can be
           octal or string, similar to the bash command. Examples:

               Execute(Chmod('file', 0755))

               env.Command('foo.out', 'foo.in',
                           [Copy('$TARGET', '$SOURCE'),
                            Chmod('$TARGET', 0755)])

               Execute(Chmod('file', "ugo+w"))

               env.Command('foo.out', 'foo.in',
                           [Copy('$TARGET', '$SOURCE'),
                            Chmod('$TARGET', "ugo+w")])

       Copy(dest, src)
           Returns an Action object that will copy the src source file or
           directory to the dest destination file or directory. Examples:

               Execute(Copy('foo.output', 'foo.input'))

               env.Command('bar.out', 'bar.in',
                           Copy('$TARGET', '$SOURCE'))

       Delete(entry, [must_exist])
           Returns an Action that deletes the specified entry, which may be a
           file or a directory tree. If a directory is specified, the entire
           directory tree will be removed. If the must_exist flag is set, then
           a Python error will be thrown if the specified entry does not
           exist; the default is must_exist=0, that is, the Action will
           silently do nothing if the entry does not exist. Examples:

               Execute(Delete('/tmp/buildroot'))

               env.Command('foo.out', 'foo.in',
                           [Delete('${TARGET.dir}'),
                            MyBuildAction])

               Execute(Delete('file_that_must_exist', must_exist=1))

       Mkdir(dir)
           Returns an Action that creates the specified directory dir .
           Examples:

               Execute(Mkdir('/tmp/outputdir'))

               env.Command('foo.out', 'foo.in',
                           [Mkdir('/tmp/builddir'),
                            Copy('/tmp/builddir/foo.in', '$SOURCE'),
                            "cd /tmp/builddir && make",
                            Copy('$TARGET', '/tmp/builddir/foo.out')])

       Move(dest, src)
           Returns an Action that moves the specified src file or directory to
           the specified dest file or directory. Examples:

               Execute(Move('file.destination', 'file.source'))

               env.Command('output_file', 'input_file',
                           [MyBuildAction,
                            Move('$TARGET', 'file_created_by_MyBuildAction')])

       Touch(file)
           Returns an Action that updates the modification time on the
           specified file. Examples:

               Execute(Touch('file_to_be_touched'))

               env.Command('marker', 'input_file',
                           [MyBuildAction,
                            Touch('$TARGET')])

   Variable Substitution
       Before executing a command, scons performs construction variable
       interpolation on the strings that make up the command line of builders.
       Variables are introduced by a $ prefix. Besides construction variables,
       scons provides the following variables for each command execution:

       CHANGED_SOURCES
           The file names of all sources of the build command that have
           changed since the target was last built.

       CHANGED_TARGETS
           The file names of all targets that would be built from sources that
           have changed since the target was last built.

       SOURCE
           The file name of the source of the build command, or the file name
           of the first source if multiple sources are being built.

       SOURCES
           The file names of the sources of the build command.

       TARGET
           The file name of the target being built, or the file name of the
           first target if multiple targets are being built.

       TARGETS
           The file names of all targets being built.

       UNCHANGED_SOURCES
           The file names of all sources of the build command that have not
           changed since the target was last built.

       UNCHANGED_TARGETS
           The file names of all targets that would be built from sources that
           have not changed since the target was last built.

           (Note that the above variables are reserved and may not be set in a
           construction environment.)

       For example, given the construction variable CC='cc', targets=['foo'],
       and sources=['foo.c', 'bar.c']:

           action='$CC -c -o $TARGET $SOURCES'

       would produce the command line:

           cc -c -o foo foo.c bar.c

       Variable names may be surrounded by curly braces ({}) to separate the
       name from the trailing characters. Within the curly braces, a variable
       name may have a Python slice subscript appended to select one or more
       items from a list. In the previous example, the string:

           ${SOURCES[1]}

       would produce:

           bar.c

       Additionally, a variable name may have the following special modifiers
       appended within the enclosing curly braces to modify the interpolated
       string:

       base
           The base path of the file name, including the directory path but
           excluding any suffix.

       dir
           The name of the directory in which the file exists.

       file
           The file name, minus any directory portion.

       filebase
           Just the basename of the file, minus any suffix and minus the
           directory.

       suffix
           Just the file suffix.

       abspath
           The absolute path name of the file.

       posix
           The POSIX form of the path, with directories separated by /
           (forward slashes) not backslashes. This is sometimes necessary on
           Windows systems when a path references a file on other (POSIX)
           systems.

       srcpath
           The directory and file name to the source file linked to this file
           through VariantDir(). If this file isn't linked, it just returns
           the directory and filename unchanged.

       srcdir
           The directory containing the source file linked to this file
           through VariantDir(). If this file isn't linked, it just returns
           the directory part of the filename.

       rsrcpath
           The directory and file name to the source file linked to this file
           through VariantDir(). If the file does not exist locally but exists
           in a Repository, the path in the Repository is returned. If this
           file isn't linked, it just returns the directory and filename
           unchanged.

       rsrcdir
           The Repository directory containing the source file linked to this
           file through VariantDir(). If this file isn't linked, it just
           returns the directory part of the filename.

       For example, the specified target will expand as follows for the
       corresponding modifiers:

           $TARGET              => sub/dir/file.x
           ${TARGET.base}       => sub/dir/file
           ${TARGET.dir}        => sub/dir
           ${TARGET.file}       => file.x
           ${TARGET.filebase}   => file
           ${TARGET.suffix}     => .x
           ${TARGET.abspath}    => /top/dir/sub/dir/file.x

           SConscript('src/SConscript', variant_dir='sub/dir')
           $SOURCE              => sub/dir/file.x
           ${SOURCE.srcpath}    => src/file.x
           ${SOURCE.srcdir}     => src

           Repository('/usr/repository')
           $SOURCE              => sub/dir/file.x
           ${SOURCE.rsrcpath}   => /usr/repository/src/file.x
           ${SOURCE.rsrcdir}    => /usr/repository/src

       Note that curly braces braces may also be used to enclose arbitrary
       Python code to be evaluated. (In fact, this is how the above modifiers
       are substituted, they are simply attributes of the Python objects that
       represent TARGET, SOURCES, etc.) See the section "Python Code
       Substitution" below, for more thorough examples of how this can be
       used.

       Lastly, a variable name may be a callable Python function associated
       with a construction variable in the environment. The function should
       take four arguments: target - a list of target nodes, source - a list
       of source nodes, env - the construction environment, for_signature - a
       Boolean value that specifies whether the function is being called for
       generating a build signature. SCons will insert whatever the called
       function returns into the expanded string:

           def foo(target, source, env, for_signature):
               return "bar"

           # Will expand $BAR to "bar baz"
           env=Environment(FOO=foo, BAR="$FOO baz")

       You can use this feature to pass arguments to a Python function by
       creating a callable class that stores one or more arguments in an
       object, and then uses them when the __call__() method is called. Note
       that in this case, the entire variable expansion must be enclosed by
       curly braces so that the arguments will be associated with the
       instantiation of the class:

           class foo(object):
               def __init__(self, arg):
                   self.arg = arg

               def __call__(self, target, source, env, for_signature):
                   return self.arg + " bar"

           # Will expand $BAR to "my argument bar baz"
           env=Environment(FOO=foo, BAR="${FOO('my argument')} baz")

       The special pseudo-variables $( and $) may be used to surround parts of
       a command line that may change without causing a rebuild--that is,
       which are not included in the signature of target files built with this
       command. All text between $( and $) will be removed from the command
       line before it is added to file signatures, and the $( and $) will be
       removed before the command is executed. For example, the command line:

           echo Last build occurred $( $TODAY $). > $TARGET

       would execute the command:

           echo Last build occurred $TODAY. > $TARGET

       but the command signature added to any target files would be:

           echo Last build occurred  . > $TARGET

   Python Code Substitution
       Any python code within ${-} pairs gets evaluated by python 'eval', with
       the python globals set to the current environment's set of construction
       variables. So in the following case:

           env['COND'] = 0
           env.Command('foo.out', 'foo.in',
               '''echo ${COND==1 and 'FOO' or 'BAR'} > $TARGET''')

       the command executed will be either

           echo FOO > foo.out

       or

           echo BAR > foo.out

       according to the current value of env['COND'] when the command is
       executed. The evaluation occurs when the target is being built, not
       when the SConscript is being read. So if env['COND'] is changed later
       in the SConscript, the final value will be used.

       Here's a more interesting example. Note that all of COND, FOO, and BAR
       are environment variables, and their values are substituted into the
       final command. FOO is a list, so its elements are interpolated
       separated by spaces.

           env=Environment()
           env['COND'] = 0
           env['FOO'] = ['foo1', 'foo2']
           env['BAR'] = 'barbar'
           env.Command('foo.out', 'foo.in',
               'echo ${COND==1 and FOO or BAR} > $TARGET')

           # Will execute this:
           #  echo foo1 foo2 > foo.out

       SCons uses the following rules when converting construction variables
       into command lines:

       String
           When the value is a string it is interpreted as a space delimited
           list of command line arguments.

       List
           When the value is a list it is interpreted as a list of command
           line arguments. Each element of the list is converted to a string.

       Other
           Anything that is not a list or string is converted to a string and
           interpreted as a single command line argument.

       Newline
           Newline characters (\n) delimit lines. The newline parsing is done
           after all other parsing, so it is not possible for arguments (e.g.
           file names) to contain embedded newline characters. This limitation
           will likely go away in a future version of SCons.

   Scanner Objects
       You can use the Scanner function to define objects to scan new file
       types for implicit dependencies. The Scanner function accepts the
       following arguments:

       function
           This can be either: 1) a Python function that will process the Node
           (file) and return a list of File Nodes representing the implicit
           dependencies (file names) found in the contents; or: 2) a
           dictionary that maps keys (typically the file suffix, but see below
           for more discussion) to other Scanners that should be called.

           If the argument is actually a Python function, the function must
           take three or four arguments:

           def scanner_function(node, env, path):

           def scanner_function(node, env, path, arg=None):

           The node argument is the internal SCons node representing the file.
           Use str(node) to fetch the name of the file, and
           node.get_contents() to fetch contents of the file. Note that the
           file is not guaranteed to exist before the scanner is called, so
           the scanner function should check that if there's any chance that
           the scanned file might not exist (for example, if it's built from
           other files).

           The env argument is the construction environment for the scan.
           Fetch values from it using the env.Dictionary() method.

           The path argument is a tuple (or list) of directories that can be
           searched for files. This will usually be the tuple returned by the
           path_function argument (see below).

           The arg argument is the argument supplied when the scanner was
           created, if any.

       name
           The name of the Scanner. This is mainly used to identify the
           Scanner internally.

       argument
           An optional argument that, if specified, will be passed to the
           scanner function (described above) and the path function (specified
           below).

       skeys
           An optional list that can be used to determine which scanner should
           be used for a given Node. In the usual case of scanning for file
           names, this argument will be a list of suffixes for the different
           file types that this Scanner knows how to scan. If the argument is
           a string, then it will be expanded into a list by the current
           environment.

       path_function
           A Python function that takes four or five arguments: a construction
           environment, a Node for the directory containing the SConscript
           file in which the first target was defined, a list of target nodes,
           a list of source nodes, and an optional argument supplied when the
           scanner was created. The path_function returns a tuple of
           directories that can be searched for files to be returned by this
           Scanner object. (Note that the FindPathDirs() function can be used
           to return a ready-made path_function for a given construction
           variable name, instead of having to write your own function from
           scratch.)

       node_class
           The class of Node that should be returned by this Scanner object.
           Any strings or other objects returned by the scanner function that
           are not of this class will be run through the node_factory
           function.

       node_factory
           A Python function that will take a string or other object and turn
           it into the appropriate class of Node to be returned by this
           Scanner object.

       scan_check
           An optional Python function that takes two arguments, a Node (file)
           and a construction environment, and returns whether the Node
           should, in fact, be scanned for dependencies. This check can be
           used to eliminate unnecessary calls to the scanner function when,
           for example, the underlying file represented by a Node does not yet
           exist.

       recursive
           An optional flag that specifies whether this scanner should be
           re-invoked on the dependency files returned by the scanner. When
           this flag is not set, the Node subsystem will only invoke the
           scanner on the file being scanned, and not (for example) also on
           the files specified by the #include lines in the file being
           scanned.  recursive may be a callable function, in which case it
           will be called with a list of Nodes found and should return a list
           of Nodes that should be scanned recursively; this can be used to
           select a specific subset of Nodes for additional scanning.

       Note that scons has a global SourceFileScanner object that is used by
       the Object(), SharedObject(), and StaticObject() builders to decide
       which scanner should be used for different file extensions. You can
       using the SourceFileScanner.add_scanner() method to add your own
       Scanner object to the scons infrastructure that builds target programs
       or libraries from a list of source files of different types:

           def xyz_scan(node, env, path):
               contents = node.get_text_contents()
               # Scan the contents and return the included files.

           XYZScanner = Scanner(xyz_scan)

           SourceFileScanner.add_scanner('.xyz', XYZScanner)

           env.Program('my_prog', ['file1.c', 'file2.f', 'file3.xyz'])

SYSTEM-SPECIFIC BEHAVIOR
       SCons and its configuration files are very portable, due largely to its
       implementation in Python. There are, however, a few portability issues
       waiting to trap the unwary.

   .C file suffix
       SCons handles the upper-case .C file suffix differently, depending on
       the capabilities of the underlying system. On a case-sensitive system
       such as Linux or UNIX, SCons treats a file with a .C suffix as a C++
       source file. On a case-insensitive system such as Windows, SCons treats
       a file with a .C suffix as a C source file.

   .F file suffix
       SCons handles the upper-case .F file suffix differently, depending on
       the capabilities of the underlying system. On a case-sensitive system
       such as Linux or UNIX, SCons treats a file with a .F suffix as a
       Fortran source file that is to be first run through the standard C
       preprocessor. On a case-insensitive system such as Windows, SCons
       treats a file with a .F suffix as a Fortran source file that should not
       be run through the C preprocessor.

   Windows: Cygwin Tools and Cygwin Python vs. Windows Pythons
       Cygwin supplies a set of tools and utilities that let users work on a
       Windows system using a more POSIX-like environment. The Cygwin tools,
       including Cygwin Python, do this, in part, by sharing an ability to
       interpret UNIX-like path names. For example, the Cygwin tools will
       internally translate a Cygwin path name like /cygdrive/c/mydir to an
       equivalent Windows pathname of C:/mydir (equivalent to C:\mydir).

       Versions of Python that are built for native Windows execution, such as
       the python.org and ActiveState versions, do not have the Cygwin path
       name semantics. This means that using a native Windows version of
       Python to build compiled programs using Cygwin tools (such as gcc,
       bison, and flex) may yield unpredictable results. "Mixing and matching"
       in this way can be made to work, but it requires careful attention to
       the use of path names in your SConscript files.

       In practice, users can sidestep the issue by adopting the following
       rules: When using gcc, use the Cygwin-supplied Python interpreter to
       run SCons; when using Microsoft Visual C/C++ (or some other Windows
       compiler) use the python.org or ActiveState version of Python to run
       SCons.

   Windows: scons.bat file
       On Windows systems, SCons is executed via a wrapper scons.bat file.
       This has (at least) two ramifications:

       First, Windows command-line users that want to use variable assignment
       on the command line may have to put double quotes around the
       assignments:

           scons "FOO=BAR" "BAZ=BLEH"

       Second, the Cygwin shell does not recognize this file as being the same
       as an scons command issued at the command-line prompt. You can work
       around this either by executing scons.bat from the Cygwin command line,
       or by creating a wrapper shell script named scons .

   MinGW
       The MinGW bin directory must be in your PATH environment variable or
       the PATH variable under the ENV construction variable for SCons to
       detect and use the MinGW tools. When running under the native Windows
       Python interpreter, SCons will prefer the MinGW tools over the Cygwin
       tools, if they are both installed, regardless of the order of the bin
       directories in the PATH variable. If you have both MSVC and MinGW
       installed and you want to use MinGW instead of MSVC, then you must
       explicitly tell SCons to use MinGW by passing

           tools=['mingw']

       to the Environment() function, because SCons will prefer the MSVC tools
       over the MinGW tools.

EXAMPLES
       To help you get started using SCons, this section contains a brief
       overview of some common tasks.

   Basic Compilation From a Single Source File
           env = Environment()
           env.Program(target = 'foo', source = 'foo.c')

       Note: Build the file by specifying the target as an argument ("scons
       foo" or "scons foo.exe"). or by specifying a dot ("scons .").

   Basic Compilation From Multiple Source Files
           env = Environment()
           env.Program(target = 'foo', source = Split('f1.c f2.c f3.c'))

   Setting a Compilation Flag
           env = Environment(CCFLAGS = '-g')
           env.Program(target = 'foo', source = 'foo.c')

   Search The Local Directory For .h Files
       Note: You do not need to set CCFLAGS to specify -I options by hand.
       SCons will construct the right -I options from CPPPATH.

           env = Environment(CPPPATH = ['.'])
           env.Program(target = 'foo', source = 'foo.c')

   Search Multiple Directories For .h Files
           env = Environment(CPPPATH = ['include1', 'include2'])
           env.Program(target = 'foo', source = 'foo.c')

   Building a Static Library
           env = Environment()
           env.StaticLibrary(target = 'foo', source = Split('l1.c l2.c'))
           env.StaticLibrary(target = 'bar', source = ['l3.c', 'l4.c'])

   Building a Shared Library
           env = Environment()
           env.SharedLibrary(target = 'foo', source = ['l5.c', 'l6.c'])
           env.SharedLibrary(target = 'bar', source = Split('l7.c l8.c'))

   Linking a Local Library Into a Program
           env = Environment(LIBS = 'mylib', LIBPATH = ['.'])
           env.Library(target = 'mylib', source = Split('l1.c l2.c'))
           env.Program(target = 'prog', source = ['p1.c', 'p2.c'])

   Defining Your Own Builder Object
       Notice that when you invoke the Builder, you can leave off the target
       file suffix, and SCons will add it automatically.

           bld = Builder(action = 'pdftex < $SOURCES > $TARGET'
                         suffix = '.pdf',
                         src_suffix = '.tex')
           env = Environment(BUILDERS = {'PDFBuilder' : bld})
           env.PDFBuilder(target = 'foo.pdf', source = 'foo.tex')

           # The following creates "bar.pdf" from "bar.tex"
           env.PDFBuilder(target = 'bar', source = 'bar')

       Note also that the above initialization overwrites the default Builder
       objects, so the Environment created above can not be used call Builders
       like env.Program(), env.Object(), env.StaticLibrary(), etc.

   Adding Your Own Builder Object to an Environment
           bld = Builder(action = 'pdftex < $SOURCES > $TARGET'
                         suffix = '.pdf',
                         src_suffix = '.tex')
           env = Environment()
           env.Append(BUILDERS = {'PDFBuilder' : bld})
           env.PDFBuilder(target = 'foo.pdf', source = 'foo.tex')
           env.Program(target = 'bar', source = 'bar.c')

       You also can use other Pythonic techniques to add to the BUILDERS
       construction variable, such as:

           env = Environment()
           env['BUILDERS]['PDFBuilder'] = bld

   Defining Your Own Scanner Object
       The following example shows an extremely simple scanner (the
       kfile_scan() function) that doesn't use a search path at all and simply
       returns the file names present on any include lines in the scanned
       file. This would implicitly assume that all included files live in the
       top-level directory:

           import re

           include_re = re.compile(r'^include\s+(\S+)$', re.M)

           def kfile_scan(node, env, path, arg):
               contents = node.get_text_contents()
               includes = include_re.findall(contents)
               return env.File(includes)

           kscan = Scanner(name = 'kfile',
                           function = kfile_scan,
                           argument = None,
                           skeys = ['.k'])
           scanners = Environment().Dictionary('SCANNERS')
           env = Environment(SCANNERS = scanners + [kscan])

           env.Command('foo', 'foo.k', 'kprocess < $SOURCES > $TARGET')

           bar_in = File('bar.in')
           env.Command('bar', bar_in, 'kprocess $SOURCES > $TARGET')
           bar_in.target_scanner = kscan

       It is important to note that you have to return a list of File nodes
       from the scan function, simple strings for the file names won't do. As
       in the examples we are showing here, you can use the File() function of
       your current Environment in order to create nodes on the fly from a
       sequence of file names with relative paths.

       Here is a similar but more complete example that searches a path of
       directories (specified as the MYPATH construction variable) for files
       that actually exist:

           import re
           import os
           include_re = re.compile(r'^include\s+(\S+)$', re.M)

           def my_scan(node, env, path, arg):
               contents = node.get_text_contents()
               includes = include_re.findall(contents)
               if includes == []:
                   return []
               results = []
               for inc in includes:
                   for dir in path:
                       file = str(dir) + os.sep + inc
                       if os.path.exists(file):
                           results.append(file)
                           break
               return env.File(results)

           scanner = Scanner(name = 'myscanner',
                            function = my_scan,
                            argument = None,
                            skeys = ['.x'],
                            path_function = FindPathDirs('MYPATH')
                            )
           scanners = Environment().Dictionary('SCANNERS')
           env = Environment(SCANNERS = scanners + [scanner],
                             MYPATH = ['incs'])

           env.Command('foo', 'foo.x', 'xprocess < $SOURCES > $TARGET')

       The FindPathDirs() function used in the previous example returns a
       function (actually a callable Python object) that will return a list of
       directories specified in the $MYPATH construction variable. It lets
       SCons detect the file incs/foo.inc , even if foo.x contains the line
       include foo.inc only. If you need to customize how the search path is
       derived, you would provide your own path_function argument when
       creating the Scanner object, as follows:

           # MYPATH is a list of directories to search for files in
           def pf(env, dir, target, source, arg):
               top_dir = Dir('#').abspath
               results = []
               if 'MYPATH' in env:
                   for p in env['MYPATH']:
                       results.append(top_dir + os.sep + p)
               return results

           scanner = Scanner(name = 'myscanner',
                            function = my_scan,
                            argument = None,
                            skeys = ['.x'],
                            path_function = pf
                            )

   Creating a Hierarchical Build
       Notice that the file names specified in a subdirectory's SConscript
       file are relative to that subdirectory.

           SConstruct:

               env = Environment()
               env.Program(target = 'foo', source = 'foo.c')

               SConscript('sub/SConscript')

           sub/SConscript:

               env = Environment()
               # Builds sub/foo from sub/foo.c
               env.Program(target = 'foo', source = 'foo.c')

               SConscript('dir/SConscript')

           sub/dir/SConscript:

               env = Environment()
               # Builds sub/dir/foo from sub/dir/foo.c
               env.Program(target = 'foo', source = 'foo.c')

   Sharing Variables Between SConscript Files
       You must explicitly Export() and Import() variables that you want to
       share between SConscript files.

           SConstruct:

               env = Environment()
               env.Program(target = 'foo', source = 'foo.c')

               Export("env")
               SConscript('subdirectory/SConscript')

           subdirectory/SConscript:

               Import("env")
               env.Program(target = 'foo', source = 'foo.c')

   Building Multiple Variants From the Same Source
       Use the variant_dir keyword argument to the SConscript function to
       establish one or more separate variant build directory trees for a
       given source directory:

           SConstruct:

               cppdefines = ['FOO']
               Export("cppdefines")
               SConscript('src/SConscript', variant_dir='foo')

               cppdefines = ['BAR']
               Export("cppdefines")
               SConscript('src/SConscript', variant_dir='bar')

           src/SConscript:

               Import("cppdefines")
               env = Environment(CPPDEFINES = cppdefines)
               env.Program(target = 'src', source = 'src.c')

       Note the use of the Export() method to set the "cppdefines" variable to
       a different value each time we call the SConscript function.

   Hierarchical Build of Two Libraries Linked With a Program
           SConstruct:

               env = Environment(LIBPATH = ['#libA', '#libB'])
               Export('env')
               SConscript('libA/SConscript')
               SConscript('libB/SConscript')
               SConscript('Main/SConscript')

           libA/SConscript:

               Import('env')
               env.Library('a', Split('a1.c a2.c a3.c'))

           libB/SConscript:

               Import('env')
               env.Library('b', Split('b1.c b2.c b3.c'))

           Main/SConscript:

               Import('env')
               e = env.Copy(LIBS = ['a', 'b'])
               e.Program('foo', Split('m1.c m2.c m3.c'))

       The '#' in the LIBPATH directories specify that they're relative to the
       top-level directory, so they don't turn into "Main/libA" when they're
       used in Main/SConscript.

       Specifying only 'a' and 'b' for the library names allows SCons to
       append the appropriate library prefix and suffix for the current
       platform (for example, 'liba.a' on POSIX systems, 'a.lib' on Windows).

   Customizing construction variables from the command line.
       The following would allow the C compiler to be specified on the command
       line or in the file custom.py.

           vars = Variables('custom.py')
           vars.Add('CC', 'The C compiler.')
           env = Environment(variables=vars)
           Help(vars.GenerateHelpText(env))

       The user could specify the C compiler on the command line:

           scons "CC=my_cc"

       or in the custom.py file:

           CC = 'my_cc'

       or get documentation on the options:

           $ scons -h

           CC: The C compiler.
               default: None
               actual: cc


   Using Microsoft Visual C++ precompiled headers
       Since windows.h includes everything and the kitchen sink, it can take
       quite some time to compile it over and over again for a bunch of object
       files, so Microsoft provides a mechanism to compile a set of headers
       once and then include the previously compiled headers in any object
       file. This technology is called precompiled headers. The general recipe
       is to create a file named "StdAfx.cpp" that includes a single header
       named "StdAfx.h", and then include every header you want to precompile
       in "StdAfx.h", and finally include "StdAfx.h" as the first header in
       all the source files you are compiling to object files. For example:

       StdAfx.h:

           #include <windows.h>
           #include <my_big_header.h>

       StdAfx.cpp:

           #include <StdAfx.h>

       Foo.cpp:

           #include <StdAfx.h>

           /* do some stuff */

       Bar.cpp:

           #include <StdAfx.h>

           /* do some other stuff */

       SConstruct:

           env=Environment()
           env['PCHSTOP'] = 'StdAfx.h'
           env['PCH'] = env.PCH('StdAfx.cpp')[0]
           env.Program('MyApp', ['Foo.cpp', 'Bar.cpp'])

       For more information see the document for the PCH builder, and the PCH
       and PCHSTOP construction variables. To learn about the details of
       precompiled headers consult the MSDN documentation for /Yc, /Yu, and
       /Yp.

   Using Microsoft Visual C++ external debugging information
       Since including debugging information in programs and shared libraries
       can cause their size to increase significantly, Microsoft provides a
       mechanism for including the debugging information in an external file
       called a PDB file. SCons supports PDB files through the PDB
       construction variable.

       SConstruct:

           env=Environment()
           env['PDB'] = 'MyApp.pdb'
           env.Program('MyApp', ['Foo.cpp', 'Bar.cpp'])

       For more information see the document for the PDB construction
       variable.

ENVIRONMENT
       SCONS_LIB_DIR
           Specifies the directory that contains the SCons Python module
           directory (e.g. /home/aroach/scons-src-0.01/src/engine).

       SCONSFLAGS
           A string of options that will be used by scons in addition to those
           passed on the command line.


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+-----------------------+
       |ATTRIBUTE TYPE |   ATTRIBUTE VALUE     |
       +---------------+-----------------------+
       |Availability   | developer/build/scons |
       +---------------+-----------------------+
       |Stability      | Volatile              |
       +---------------+-----------------------+
SEE ALSO
       scons User Manual, scons Design Document, scons source code.

AUTHORS
       Originally: Steven Knight <knight@baldmt.com> and Anthony Roach
       <aroach@electriceyeball.com> Since 2010: The SCons Development Team
       <scons-dev@scons.org>

AUTHORS
       Steven Knight
           Author.

       Steven Knight and the SCons Development Team

COPYRIGHT
       Copyright (C) 2004 - 2016 The SCons Foundation



NOTES
       This software was built from source available at
       https://github.com/oracle/solaris-userland.  The original community
       source was downloaded from
       https://sourceforge.net/projects/scons/files/scons/2.5.1/scons-2.5.1.tar.gz/download

       Further information about this software can be found on the open source
       community website at http://www.scons.org/.



SCons 2.5.1 version 2.5.1                       <pubdate>2004 - 2016</pubdate>
                                                                      SCONS(1)