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.

   erlc flags file1.ext file2.ext...
       Compiles one or more files. The files must include the extension, for example,  .erl  for  Erlang  source
       code, or .yrl for Yecc source code. Erlc uses the extension to invoke the correct compiler.

   Generally Useful Flags
       The following flags are supported:

       -I <Directory>
         Instructs  the  compiler to search for include files in the Directory. 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 specified 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.

       -enable-feature <Feature>
         Enables the feature feature during compilation. The special feature all  can  be  used  to  enable  all
         features.

       -disable-feature <feature>
         Disables the feature feature during compilation. The special feature all can be used to disable all non
         permanent features.

       -list-features
         List  short  descriptions  of  the current configurable features. Non-configurable features (those with
         status rejected or permanent) will not be shown.

       -describe-feature <feature>
         Show long description and history of feature feature.

       -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 example, 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 containing 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 rebuilding 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 customized 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 systools: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 situations 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
           compile 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 randomly 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, allowing 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, yecc, snmp

Ericsson AB                                        erts 15.2.3                                           erlc(1)