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Updated: Wednesday, February 9, 2022

erlc (1)


erlc - Compiler


Please see following description for synopsis


erlc(1)                          User Commands                         erlc(1)

       erlc - Compiler

       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.

       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-

       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.

           Defines a macro.

           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.

           Makes all warnings into errors.

           Sets  warning level to Number. Defaults to 1. To turn off warnings,
           use -W0.

           Same as -W1. Default.

           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.

           Do not use the compile server.

           Use the compile server.

           Produces a Makefile rule to track header dependencies. The rule  is
           sent to stdout. No object file is produced.

           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.

           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.

           In conjunction with option -M or -MF, adds a phony target for  each

           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.

           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

         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.

       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.

       The following compilers are supported:

           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.

           Erlang assembler source code. It generates a .beam file.

           Supported options: same as for .erl.

           Erlang core source code. It generates a .beam file.

           Supported options: same as for .erl.

           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 for SNMP. It generates a .bin file.

           Supported options: -I, -o, -W.

           A compiled MIB for SNMP. It generates a .hrl file.

           Supported options: -o, -v.

           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-

           Supported option: -o.

           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.

           IC file. It runs the IDL compiler.

           Supported options: -I, -o.

       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.)

           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.

           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.

           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.

       erl(1), compile(3), yecc(3), snmp(3)

Ericsson AB                        erts 12.0                           erlc(1)