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argc (1t)

Name

argc - tive, tcl_library, tcl_nonwordchars, tcl_patchLevel, tcl_pkgPath, tcl_platform, tcl_precision, tcl_rcFileName, tcl_traceCompile, tcl_traceExec, tcl_wordchars, tcl_version - Variables used by Tcl

Synopsis

Please see following description for synopsis

Description

tclvars(1t)                  Tcl Built-In Commands                 tclvars(1t)



______________________________________________________________________________

NAME
       argc,  argv,  argv0, auto_path, env, errorCode, errorInfo, tcl_interac-
       tive,  tcl_library,  tcl_nonwordchars,   tcl_patchLevel,   tcl_pkgPath,
       tcl_platform,    tcl_precision,    tcl_rcFileName,    tcl_traceCompile,
       tcl_traceExec, tcl_wordchars, tcl_version - Variables used by Tcl
______________________________________________________________________________

DESCRIPTION
       The following global variables are created and managed automatically by
       the Tcl library.  Except where noted below, these variables should nor-
       mally be treated as  read-only  by  application-specific  code  and  by
       users.

       auto_path
              If set, then it must contain a valid Tcl list giving directories
              to search during auto-load  operations  (including  for  package
              index  files  when  using  the default package unknown handler).
              This variable is  initialized  during  startup  to  contain,  in
              order:  the  directories  listed  in  the TCLLIBPATH environment
              variable, the directory named by the  tcl_library  global  vari-
              able,  the  parent  directory  of  tcl_library,  the directories
              listed in the tcl_pkgPath  variable.   Additional  locations  to
              look  for  files and package indices should normally be added to
              this variable using lappend.

              Additional variables relating to package management exist.  More
              details  are listed in the VARIABLES section of the library man-
              ual page.

       env    This variable is maintained by Tcl as an  array  whose  elements
              are  the environment variables for the process.  Reading an ele-
              ment will return the  value  of  the  corresponding  environment
              variable.   Setting an element of the array will modify the cor-
              responding environment variable or create a new one if  it  does
              not  already exist.  Unsetting an element of env will remove the
              corresponding environment variable.  Changes to  the  env  array
              will  affect the environment passed to children by commands like
              exec.  If the entire env array is unset then Tcl will stop moni-
              toring env accesses and will not update environment variables.

              Under Windows, the environment variables PATH and COMSPEC in any
              capitalization are converted automatically to upper  case.   For
              instance,  the  PATH variable could be exported by the operating
              system as "path", "Path", "PaTh", etc., causing otherwise simple
              Tcl code to have to support many special cases.  All other envi-
              ronment variables inherited by Tcl are left unmodified.  Setting
              an  env  array  variable to blank is the same as unsetting it as
              this is the behavior of the underlying Windows OS.  It should be
              noted that relying on an existing and empty environment variable
              will not work on Windows and is discouraged  for  cross-platform
              usage.

              The following elements of env are special to Tcl:

              env(HOME)
                     This  environment variable, if set, gives the location of
                     the directory considered to be the  current  user's  home
                     directory, and to which a call of cd without arguments or
                     with just "~" as an argument will change into. Most plat-
                     forms set this correctly by default; it does not normally
                     need to be set by user code.

              env(TCL_LIBRARY)
                     If set, then it specifies the location of  the  directory
                     containing  library  scripts  (the value of this variable
                     will be assigned to the tcl_library variable  and  there-
                     fore  returned  by  the  command  info library).  If this
                     variable is not set then a default value is used.

                     Note that this environment variable should  not  normally
                     be set.

              env(TCLLIBPATH)
                     If  set,  then  it  must  contain a valid Tcl list giving
                     directories  to  search  during   auto-load   operations.
                     Directories must be specified in Tcl format, using "/" as
                     the path separator, regardless of platform.   This  vari-
                     able  is  only used when initializing the auto_path vari-
                     able.

              env(TCL_TZ), env(TZ)
                     These specify the default timezone used for  parsing  and
                     formatting  times and dates in the clock command. On many
                     platforms, the TZ environment variable is set up  by  the
                     operating system.

              env(LC_ALL), env(LC_MESSAGES), env(LANG)
                     These  environment variables are used by the msgcat pack-
                     age to determine what locale to format messages using.

              env(TCL_INTERP_DEBUG_FRAME)
                     If existing, it has the same  effect  as  running  interp
                     debug  {}  -frame 1 as the very first command of each new
                     Tcl interpreter.

       errorCode
              This variable holds the value of the  -errorcode  return  option
              set  by the most recent error that occurred in this interpreter.
              This list value  represents  additional  information  about  the
              error  in  a  form  that  is easy to process with programs.  The
              first element of the list identifies a general class of  errors,
              and  determines the format of the rest of the list.  The follow-
              ing formats for -errorcode return options are used  by  the  Tcl
              core; individual applications may define additional formats.

              ARITH code msg
                     This format is used when an arithmetic error occurs (e.g.
                     an attempt to divide zero by zero in the  expr  command).
                     Code  identifies  the  precise  error  and msg provides a
                     human-readable description of the error.   Code  will  be
                     either DIVZERO (for an attempt to divide by zero), DOMAIN
                     (if an argument is outside the domain of a function, such
                     as  acos(-3)), IOVERFLOW (for integer overflow), OVERFLOW
                     (for a floating-point overflow), or UNKNOWN (if the cause
                     of the error cannot be determined).

                     Detection of these errors depends in part on the underly-
                     ing hardware and system libraries.

              CHILDKILLED pid sigName msg
                     This format is used when a child process has been  killed
                     because  of  a  signal.   The  pid  element  will  be the
                     process's identifier (in decimal).  The  sigName  element
                     will  be  the symbolic name of the signal that caused the
                     process to terminate; it will be one of  the  names  from
                     the include file signal.h, such as SIGPIPE.  The msg ele-
                     ment will be a short  human-readable  message  describing
                     the  signal,  such as "write on pipe with no readers" for
                     SIGPIPE.

              CHILDSTATUS pid code
                     This format is used when a child process has exited  with
                     a  non-zero  exit  status.   The  pid element will be the
                     process's identifier (in decimal) and  the  code  element
                     will  be  the  exit code returned by the process (also in
                     decimal).

              CHILDSUSP pid sigName msg
                     This format is used when a child process  has  been  sus-
                     pended  because of a signal.  The pid element will be the
                     process's identifier, in decimal.   The  sigName  element
                     will  be  the symbolic name of the signal that caused the
                     process to suspend; this will be one of  the  names  from
                     the include file signal.h, such as SIGTTIN.  The msg ele-
                     ment will be a short  human-readable  message  describing
                     the signal, such as "background tty read" for SIGTTIN.

              NONE   This format is used for errors where no additional infor-
                     mation is available for  an  error  besides  the  message
                     returned  with  the error.  In these cases the -errorcode
                     return option will consist of a list containing a  single
                     element whose contents are NONE.

              POSIX errName msg
                     If  the  first  element is POSIX, then the error occurred
                     during a POSIX kernel call.   The  errName  element  will
                     contain  the  symbolic  name  of the error that occurred,
                     such as ENOENT; this will be one of the values defined in
                     the  include  file  errno.h.   The  msg element will be a
                     human-readable message corresponding to errName, such  as
                     "no such file or directory" for the ENOENT case.

              TCL ...
                     Indicates  some  sort of problem generated in relation to
                     Tcl itself, e.g. a failure to look up a channel or  vari-
                     able.

              To  set  the  -errorcode  return option, applications should use
              library procedures such as Tcl_SetObjErrorCode, Tcl_SetReturnOp-
              tions,  and  Tcl_PosixError,  or  they may invoke the -errorcode
              option of the return command.  If none of these methods for set-
              ting  the  error  code  has  been used, the Tcl interpreter will
              reset the variable to NONE after the next error.

       errorInfo
              This variable holds the value of the  -errorinfo  return  option
              set  by the most recent error that occurred in this interpreter.
              This string value will contain one or more lines identifying the
              Tcl  commands  and  procedures that were being executed when the
              most recent error occurred.  Its contents take  the  form  of  a
              stack  trace  showing  the  various nested Tcl commands that had
              been invoked at the time of the error.

       tcl_library
              This variable holds the name of a directory containing the  sys-
              tem library of Tcl scripts, such as those used for auto-loading.
              The value of this variable is returned by the info library  com-
              mand.   See  the library manual entry for details of the facili-
              ties provided by the Tcl script library.  Normally each applica-
              tion  or  package  will have its own application-specific script
              library in addition to the Tcl script library; each  application
              should  set  a  global  variable  with  a name like $app_library
              (where app is the application's name) to hold the  network  file
              name  for  that  application's  library  directory.  The initial
              value of tcl_library is set when an interpreter  is  created  by
              searching  several different directories until one is found that
              contains an appropriate Tcl startup script.  If the  TCL_LIBRARY
              environment  variable  exists,  then  the  directory it names is
              checked first.  If TCL_LIBRARY is not set or doesn't refer to an
              appropriate directory, then Tcl checks several other directories
              based on a compiled-in default location,  the  location  of  the
              binary  containing  the  application,  and  the  current working
              directory.

       tcl_patchLevel
              When an interpreter is created Tcl initializes this variable  to
              hold  a  string  giving the current patch level for Tcl, such as
              8.4.16 for Tcl 8.4 with the first sixteen official  patches,  or
              8.5b3  for the third beta release of Tcl 8.5.  The value of this
              variable is returned by the info patchlevel command.

       tcl_pkgPath
              This variable holds a list of directories indicating where pack-
              ages  are  normally  installed.   It is not used on Windows.  It
              typically contains either one or two entries; if it contains two
              entries,  the  first is normally a directory for platform-depen-
              dent packages (e.g., shared library binaries) and the second  is
              normally  a  directory  for platform-independent packages (e.g.,
              script files). Typically a package is installed as  a  subdirec-
              tory  of  one  of  the  entries in the tcl_pkgPath variable. The
              directories in the tcl_pkgPath variable are included by  default
              in the auto_path variable, so they and their immediate subdirec-
              tories are automatically searched for  packages  during  package
              require commands.  Note: tcl_pkgPath is not intended to be modi-
              fied by the application.  Its value is  added  to  auto_path  at
              startup;  changes to tcl_pkgPath are not reflected in auto_path.
              If you want Tcl to search additional  directories  for  packages
              you  should add the names of those directories to auto_path, not
              tcl_pkgPath.

       tcl_platform
              This is an associative array whose elements contain  information
              about  the platform on which the application is running, such as
              the name of the operating system, its  current  release  number,
              and  the  machine's  instruction set.  The elements listed below
              will always be defined, but they may have empty strings as  val-
              ues  if  Tcl  could  not  retrieve any relevant information.  In
              addition, extensions and applications may add additional  values
              to the array.  The predefined elements are:

              byteOrder
                     The  native  byte order of this machine: either littleEn-
                     dian or bigEndian.

              debug  If this variable exists, then the  interpreter  was  com-
                     piled  with  and  linked  to  a debug-enabled C run-time.
                     This variable will only exist on  Windows,  so  extension
                     writers  can  specify  which package to load depending on
                     the C run-time library that is in use.  This  is  not  an
                     indication that this core contains symbols.

              engine The  name  of  the Tcl language implementation.  When the
                     interpreter is first created, this is always set  to  the
                     string Tcl.

              machine
                     The  instruction  set  executed  by this machine, such as
                     intel, PPC, 68k, or sun4m.  On UNIX machines, this is the
                     value returned by uname -m.

              os     The name of the operating system running on this machine,
                     such as Windows NT or SunOS.  On UNIX machines,  this  is
                     the value returned by uname -s.

              osVersion
                     The  version  number  for the operating system running on
                     this machine.   On  UNIX  machines,  this  is  the  value
                     returned by uname -r.

              pathSeparator
                     The  character  that  should  be  used to split PATH-like |
                     environment variables into their  corresponding  list  of |
                     directory names.

              platform
                     Either  windows,  or  unix.   This identifies the general
                     operating environment of the machine.

              pointerSize
                     This gives the size  of  the  native-machine  pointer  in
                     bytes  (strictly,  it is same as the result of evaluating
                     sizeof(void*) in C.)

              threaded
                     If this variable exists, then the  interpreter  was  com-
                     piled with threads enabled.

              user   This  identifies  the  current  user  based  on the login
                     information available on the platform.  This value  comes
                     from  the  getuid()  and getpwuid() system calls on Unix,
                     and the value from the GetUserName() system call on  Win-
                     dows.

              wordSize
                     This  gives  the size of the native-machine word in bytes
                     (strictly,  it  is  same  as  the  result  of  evaluating
                     sizeof(long) in C.)

       tcl_precision
              This  variable  controls  the  number of digits to generate when
              converting floating-point values to strings.  It defaults to  0.
              Applications  should  not  change this value; it is provided for
              compatibility with legacy code.

              The default value of 0 is special, meaning that Tcl should  con-
              vert numbers using as few digits as possible while still distin-
              guishing any floating point number from its nearest  neighbours.
              It  differs  from using an arbitrarily high value for tcl_preci-
              sion in that an inexact number like  1.4  will  convert  as  1.4
              rather  than 1.3999999999999999 even though the latter is nearer
              to the exact value of the binary number.

              If tcl_precision is not zero, then when Tcl converts a  floating
              point  number,  it  creates  a decimal representation of at most
              tcl_precision significant digits; the result may be  shorter  if
              the shorter result represents the original number exactly. If no
              result of at most tcl_precision digits is an  exact  representa-
              tion  of  the  original  number,  the one that is closest to the
              original number is chosen.  If the  original  number  lies  pre-
              cisely  between  two  equally  accurate decimal representations,
              then the one with an even value for the least significant  digit
              is chosen; for instance, if tcl_precision is 3, then 0.3125 will
              convert to 0.312, not 0.313, while 0.6875 will convert to 0.688,
              not  0.687.  Any  string  of  trailing  zeroes  that  remains is
              trimmed.

              a tcl_precision value of 17 digits is "perfect" for IEEE  float-
              ing-point  in  that it allows double-precision values to be con-
              verted to strings and back to binary with no  loss  of  informa-
              tion.  For  this  reason,  you  will  often see it as a value in
              legacy code that must run on Tcl versions before 8.5. It  is  no
              longer  recommended;  as  noted  above, a zero value is the pre-
              ferred method.

              All interpreters in a thread share a single tcl_precision value:
              changing  it  in  one  interpreter  will affect all other inter-
              preters as well.  Safe interpreters are not  allowed  to  modify
              the variable.

              Valid values for tcl_precision range from 0 to 17.

       tcl_rcFileName
              This variable is used during initialization to indicate the name
              of a user-specific startup file.  If it is set  by  application-
              specific  initialization,  then  the Tcl startup code will check
              for the existence of this file and source it if it exists.   For
              example,  for wish the variable is set to ~/.wishrc for Unix and
              ~/wishrc.tcl for Windows.

       tcl_traceCompile
              The value of this variable can be set to control how much  trac-
              ing  information  is  displayed during bytecode compilation.  By
              default, tcl_traceCompile is zero and  no  information  is  dis-
              played.  Setting tcl_traceCompile to 1 generates a one-line sum-
              mary in stdout whenever a procedure or top-level command is com-
              piled.   Setting  it to 2 generates a detailed listing in stdout
              of the bytecode instructions emitted during  every  compilation.
              This variable is useful in tracking down suspected problems with
              the Tcl compiler.

              This variable and functionality only exist if  TCL_COMPILE_DEBUG
              was defined during Tcl's compilation.

       tcl_traceExec
              The  value of this variable can be set to control how much trac-
              ing information is  displayed  during  bytecode  execution.   By
              default,  tcl_traceExec is zero and no information is displayed.
              Setting tcl_traceExec to 1 generates a one-line trace in  stdout
              on  each  call  to a Tcl procedure.  Setting it to 2 generates a
              line of output whenever any Tcl command is invoked that contains
              the name of the command and its arguments.  Setting it to 3 pro-
              duces a detailed trace showing  the  result  of  executing  each
              bytecode  instruction.   Note that when tcl_traceExec is 2 or 3,
              commands such as set and incr that have been  entirely  replaced
              by  a  sequence of bytecode instructions are not shown.  Setting
              this variable is useful in tracking down suspected problems with
              the bytecode compiler and interpreter.

              This  variable and functionality only exist if TCL_COMPILE_DEBUG
              was defined during Tcl's compilation.

       tcl_wordchars
              The value of this variable is a regular expression that  can  be
              set  to  control  what  are  considered  "word"  characters, for
              instances like selecting a word by double-clicking  in  text  in
              Tk.   It  is platform dependent.  On Windows, it defaults to \S,
              meaning anything but a Unicode space  character.   Otherwise  it
              defaults  to  \w,  which  is any Unicode word character (number,
              letter, or underscore).

       tcl_nonwordchars
              The value of this variable is a regular expression that  can  be
              set  to  control  what are considered "non-word" characters, for
              instances like selecting a word by double-clicking  in  text  in
              Tk.   It  is platform dependent.  On Windows, it defaults to \s,
              meaning any Unicode space character.  Otherwise it  defaults  to
              \W, which is anything but a Unicode word character (number, let-
              ter, or underscore).

       tcl_version
              When an interpreter is created Tcl initializes this variable  to
              hold the version number for this version of Tcl in the form x.y.
              Changes to x represent major changes with probable incompatibil-
              ities  and  changes  to  y  represent small enhancements and bug
              fixes that retain backward compatibility.   The  value  of  this
              variable is returned by the info tclversion command.

OTHER GLOBAL VARIABLES
       The  following variables are only guaranteed to exist in tclsh and wish
       executables; the Tcl library does not define them itself but  many  Tcl
       environments do.

       argc  The number of arguments to tclsh or wish.

       argv  Tcl list of arguments to tclsh or wish.

       argv0 The script that tclsh or wish started executing (if it was speci-
             fied) or otherwise the name by which tclsh or wish was invoked.

       tcl_interactive
             Contains 1 if tclsh or wish is running interactively  (no  script
             was  specified  and  standard input is a terminal-like device), 0
             otherwise.

EXAMPLES
       To add a directory to the collection of locations searched  by  package
       require,  e.g.,  because of some application-specific packages that are
       used, the auto_path variable needs to be updated:

              lappend ::auto_path [file join [pwd] "theLibDir"]

       A simple though not very robust way to handle command line arguments of
       the  form  "-foo  1  -bar 2" is to load them into an array having first
       loaded in the default settings:
              array set arguments {-foo 0 -bar 0 -grill 0}
              array set arguments $::argv
              puts "foo is $arguments(-foo)"
              puts "bar is $arguments(-bar)"
              puts "grill is $arguments(-grill)"

       The argv0 global variable can be used (in  conjunction  with  the  info
       script  command)  to determine whether the current script is being exe-
       cuted as the main script or  loaded  as  a  library.   This  is  useful
       because  it  allows  a single script to be used as both a library and a
       demonstration of that library:

              if {$::argv0 eq [info script]} {
                  # running as: tclsh example.tcl
              } else {
                  package provide Example 1.0
              }


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | runtime/tcl-8    |
       +---------------+------------------+
       |Stability      | Uncommitted      |
       +---------------+------------------+
SEE ALSO
       eval(n), library(n), tclsh(1), tkvars(n), wish(1)

KEYWORDS
       arithmetic, bytecode, compiler, error, environment,  POSIX,  precision,
       subprocess, user, variables



NOTES
       This     software     was    built    from    source    available    at
       https://github.com/oracle/solaris-userland.   The  original   community
       source was downloaded from  http://prdownloads.sourceforge.net/tcl/tcl-
       core8.6.7-src.tar.gz

       Further information about this software can be found on the open source
       community website at https://www.tcl.tk/.



Tcl                                   8.0                          tclvars(1t)