erlc - Compiler
Please see following description for synopsis
erlc(1) User Commands erlc(1)
NAME
erlc - Compiler
DESCRIPTION
The erlc program provides a common way to run all compilers in the
Erlang system. Depending on the extension of each input file, erlc
invokes the appropriate compiler. Regardless of which compiler is used,
the same flags are used to provide parameters, such as include paths
and output directory.
The current working directory, ".", is not included in the code path
when running the compiler. This is to avoid loading Beam files from the
current working directory that could potentially be in conflict with
the compiler or the Erlang/OTP system used by the compiler.
EXPORTS
erlc flags file1.ext file2.ext...
Compiles one or more files. The files must include the exten-
sion, for example, .erl for Erlang source code, or .yrl for Yecc
source code. Erlc uses the extension to invoke the correct com-
piler.
GENERALLY USEFUL FLAGS
The following flags are supported:
-I <Directory>:
Instructs the compiler to search for include files in the Direc-
tory. When encountering an -include or -include_lib directive, the
compiler searches for header files in the following directories:
* ".", the current working directory of the file server
* The base name of the compiled file
* The directories specified using option -I; the directory speci-
fied last is searched first
-o <Directory>:
The directory where the compiler is to place the output files.
Defaults to the current working directory.
-D<Name>:
Defines a macro.
-D<Name>=<Value>:
Defines a macro with the specified value. The value can be any
Erlang term. Depending on the platform, the value may need to be
quoted if the shell itself interprets certain characters. On Unix,
terms containing tuples and lists must be quoted. Terms containing
spaces must be quoted on all platforms.
-WError:
Makes all warnings into errors.
-W<Number>:
Sets warning level to Number. Defaults to 1. To turn off warnings,
use -W0.
-W:
Same as -W1. Default.
-v:
Enables verbose output.
-b <Output_type>:
Specifies the type of output file. Output_type is the same as the
file extension of the output file, but without the period. This
option is ignored by compilers that have a single output format.
-no-server:
Do not use the compile server.
-server:
Use the compile server.
-M:
Produces a Makefile rule to track header dependencies. The rule is
sent to stdout. No object file is produced.
-MMD:
Generate dependencies as a side-effect. The object file will be
produced as normal. This option overrides the option -M.
-MF <Makefile>:
As option -M, except that the Makefile is written to Makefile. No
object file is produced.
-MD:
Same as -M -MF <File>.Pbeam.
-MT <Target>:
In conjunction with option -M or -MF, changes the name of the rule
emitted to Target.
-MQ <Target>:
As option -MT, except that characters special to make/1 are quoted.
-MP:
In conjunction with option -M or -MF, adds a phony target for each
dependency.
-MG:
In conjunction with option -M or -MF, considers missing headers as
generated files and adds them to the dependencies.
--:
Signals that no more options will follow. The rest of the arguments
is treated as filenames, even if they start with hyphens.
+<Term>:
A flag starting with a plus (+) rather than a hyphen is converted
to an Erlang term and passed unchanged to the compiler. For exam-
ple, option export_all for the Erlang compiler can be specified as
follows:
erlc +export_all file.erl
Depending on the platform, the value may need to be quoted if the
shell itself interprets certain characters. On Unix, terms contain-
ing tuples and lists must be quoted. Terms containing spaces must
be quoted on all platforms.
SPECIAL FLAGS
The following flags are useful in special situations, such as rebuild-
ing the OTP system:
-pa <Directory>:
Appends Directory to the front of the code path in the invoked
Erlang emulator. This can be used to invoke another compiler than
the default one.
-pz <Directory>:
Appends Directory to the code path in the invoked Erlang emulator.
SUPPORTED COMPILERS
The following compilers are supported:
.erl:
Erlang source code. It generates a .beam file.
Options -P, -E, and -S are equivalent to +'P', +'E', and +'S',
except that it is not necessary to include the single quotes to
protect them from the shell.
Supported options: -I, -o, -D, -v, -W, -b.
.S:
Erlang assembler source code. It generates a .beam file.
Supported options: same as for .erl.
.core:
Erlang core source code. It generates a .beam file.
Supported options: same as for .erl.
.yrl:
Yecc source code. It generates an .erl file.
Use option -I with the name of a file to use that file as a custom-
ized prologue file (option includefile).
Supported options: -o, -v, -I, -W.
.mib:
MIB for SNMP. It generates a .bin file.
Supported options: -I, -o, -W.
.bin:
A compiled MIB for SNMP. It generates a .hrl file.
Supported options: -o, -v.
.rel:
Script file. It generates a boot file.
Use option -I to name directories to be searched for application
files (equivalent to the path in the option list for sys-
tools:make_script/2).
Supported option: -o.
.asn1:
ASN1 file. It creates an .erl, .hrl, and .asn1db file from an .asn1
file. Also compiles the .erl using the Erlang compiler unless
option +noobj is specified.
Supported options: -I, -o, -b, -W.
.idl:
IC file. It runs the IDL compiler.
Supported options: -I, -o.
COMPILE SERVER
The compile server can be used to potentially speed up the build of
multi-file projects by avoiding to start an Erlang system for each file
to compile. Whether it will speed up the build depends on the nature of
the project and the build machine.
By default, the compile server is not used. It can be enabled by giving
erlc the option -server or by setting the environment variable
ERLC_USE_SERVER to yes or true.
When the compile server is enabled, erlc will automatically use the
server if it is started and start the server if has not already
started. The server will terminate itself when it has been idle for
some number of seconds.
erlc and the compile server communicate using the Erlang distribution.
The compile server is started as a hidden node, with a name that
includes the current user. Thus, each user on a computer has their own
compile server.
Using the compile server does not always speed up the build, as the
compile server sometimes must be restarted to ensure correctness. Here
are some examples of situtations that force a restart:
* erlc wants to use a different version of Erlang than the compile
server is using.
* erlc wants to use different options for erl than the compile server
was started with. (A change to code path using the option -pa could
cause different parse transforms to be loaded. To be safe, the com-
pile server will be restarted when any erl option is changed.)
* If the current working directory for erlc is different from the
working directory active when the compile server was started, and
if the compile server has active jobs, it will be restarted as soon
as those jobs have finished. (Build systems that build files ran-
domly across multiple directories in parallel will probably not
benefit from the compile server.)
ENVIRONMENT VARIABLES
ERLC_EMULATOR:
The command for starting the emulator. Defaults to erl in the same
directory as the erlc program itself, or, if it does not exist, erl
in any of the directories specified in environment variable PATH.
ERLC_USE_SERVER:
Allowed values are yes or true to use the compile server, and no or
false to not use the compile server. If other values are given,
erlc will print a warning message and continue.
ERLC_SERVER_ID:
Tells erlc to identify the compile server by the given name, allow-
ing a single user to run multiple unrelated builds in parallel
without them affecting each other, which can be useful for shared
build machines and the like. The name must be alphanumeric, and it
defaults to being empty.
SEE ALSO
erl(1), compile(3), yecc(3), snmp(3)
Ericsson AB erts 12.2 erlc(1)