File: autoconf.info,  Node: autom4te Invocation,  Next: Customizing autom4te,  Up: Using autom4te

8.2.1 Invoking ‘autom4te’
-------------------------

The command line arguments are modeled after M4's:

     autom4te OPTIONS FILES

where the FILES are directly passed to ‘m4’.  By default, GNU M4 is
found during configuration, but the environment variable ‘M4’ can be set
to tell ‘autom4te’ where to look.  In addition to the regular expansion,
it handles the replacement of the quadrigraphs (*note Quadrigraphs::),
and of ‘__oline__’, the current line in the output.  It supports an
extended syntax for the FILES:

‘FILE.m4f’
     This file is an M4 frozen file.  Note that _all the previous files
     are ignored_.  See the ‘--melt’ option for the rationale.

‘FILE?’
     If found in the library path, the FILE is included for expansion,
     otherwise it is ignored instead of triggering a failure.


   Of course, it supports the Autoconf common subset of options:

‘--help’
‘-h’
     Print a summary of the command line options and exit.

‘--version’
‘-V’
     Print the version number of Autoconf and exit.

‘--verbose’
‘-v’
     Report processing steps.

‘--debug’
‘-d’
     Don't remove the temporary files and be even more verbose.

‘--include=DIR’
‘-I DIR’
     Also look for input files in DIR.  Multiple invocations accumulate.

‘--output=FILE’
‘-o FILE’
     Save output (script or trace) to FILE.  The file ‘-’ stands for the
     standard output.


   As an extension of ‘m4’, it includes the following options:

‘--warnings=CATEGORY[,CATEGORY...]’
‘-WCATEGORY[,CATEGORY...]’
     Enable or disable warnings related to each CATEGORY.  *Note
     m4_warn::, for a comprehensive list of categories.  Special values
     include:

     ‘all’
          Enable all categories of warnings.

     ‘none’
          Disable all categories of warnings.

     ‘error’
          Treat all warnings as errors.

     ‘no-CATEGORY’
          Disable warnings falling into CATEGORY.

     The environment variable ‘WARNINGS’ may also be set to a
     comma-separated list of warning categories to enable or disable.
     It is interpreted exactly the same way as the argument of
     ‘--warnings’, but unknown categories are silently ignored.  The
     command line takes precedence; for instance, if ‘WARNINGS’ is set
     to ‘obsolete’, but ‘-Wnone’ is given on the command line, no
     warnings will be issued.

     Some categories of warnings are on by default.  Again, for details
     see *note m4_warn::.

‘--melt’
‘-M’
     Do not use frozen files.  Any argument ‘FILE.m4f’ is replaced by
     ‘FILE.m4’.  This helps tracing the macros which are executed only
     when the files are frozen, typically ‘m4_define’.  For instance,
     running:

          autom4te --melt 1.m4 2.m4f 3.m4 4.m4f input.m4

     is roughly equivalent to running:

          m4 1.m4 2.m4 3.m4 4.m4 input.m4

     while

          autom4te 1.m4 2.m4f 3.m4 4.m4f input.m4

     is equivalent to:

          m4 --reload-state=4.m4f input.m4

‘--freeze’
‘-F’
     Produce a frozen state file.  ‘autom4te’ freezing is stricter than
     M4's: it must produce no warnings, and no output other than empty
     lines (a line with white space is _not_ empty) and comments
     (starting with ‘#’).  Unlike ‘m4’'s similarly-named option, this
     option takes no argument:

          autom4te 1.m4 2.m4 3.m4 --freeze --output=3.m4f

     corresponds to

          m4 1.m4 2.m4 3.m4 --freeze-state=3.m4f

‘--mode=OCTAL-MODE’
‘-m OCTAL-MODE’
     Set the mode of the non-traces output to OCTAL-MODE; by default
     ‘0666’.


   As another additional feature over ‘m4’, ‘autom4te’ caches its
results.  GNU M4 is able to produce a regular output and traces at the
same time.  Traces are heavily used in the GNU Build System:
‘autoheader’ uses them to build ‘config.h.in’, ‘autoreconf’ to determine
what GNU Build System components are used, ‘automake’ to "parse"
‘configure.ac’ etc.  To avoid recomputation, traces are cached while
performing regular expansion, and conversely.  This cache is (actually,
the caches are) stored in the directory ‘autom4te.cache’.  _It can
safely be removed_ at any moment (especially if for some reason
‘autom4te’ considers it trashed).

‘--cache=DIRECTORY’
‘-C DIRECTORY’
     Specify the name of the directory where the result should be
     cached.  Passing an empty value disables caching.  Be sure to pass
     a relative file name, as for the time being, global caches are not
     supported.

‘--no-cache’
     Don't cache the results.

‘--force’
‘-f’
     If a cache is used, consider it obsolete (but update it anyway).


   Because traces are so important to the GNU Build System, ‘autom4te’
provides high level tracing features as compared to M4, and helps
exploiting the cache:

‘--trace=MACRO[:FORMAT]’
‘-t MACRO[:FORMAT]’
     Trace the invocations of MACRO according to the FORMAT.  Multiple
     ‘--trace’ arguments can be used to list several macros.  Multiple
     ‘--trace’ arguments for a single macro are not cumulative; instead,
     you should just make FORMAT as long as needed.

     The FORMAT is a regular string, with newlines if desired, and
     several special escape codes.  It defaults to ‘$f:$l:$n:$%’.  It
     can use the following special escapes:

     ‘$$’
          The character ‘$’.

     ‘$f’
          The file name from which MACRO is called.

     ‘$l’
          The line number from which MACRO is called.

     ‘$d’
          The depth of the MACRO call.  This is an M4 technical detail
          that you probably don't want to know about.

     ‘$n’
          The name of the MACRO.

     ‘$NUM’
          The NUMth argument of the call to MACRO.

     ‘$@’
     ‘$SEP@’
     ‘${SEPARATOR}@’
          All the arguments passed to MACRO, separated by the character
          SEP or the string SEPARATOR (‘,’ by default).  Each argument
          is quoted, i.e., enclosed in a pair of square brackets.

     ‘$*’
     ‘$SEP*’
     ‘${SEPARATOR}*’
          As above, but the arguments are not quoted.

     ‘$%’
     ‘$SEP%’
     ‘${SEPARATOR}%’
          As above, but the arguments are not quoted, all new line
          characters in the arguments are smashed, and the default
          separator is ‘:’.

          The escape ‘$%’ produces single-line trace outputs (unless you
          put newlines in the ‘separator’), while ‘$@’ and ‘$*’ do not.

     *Note autoconf Invocation::, for examples of trace uses.

‘--preselect=MACRO’
‘-p MACRO’
     Cache the traces of MACRO, but do not enable traces.  This is
     especially important to save CPU cycles in the future.  For
     instance, when invoked, ‘autoconf’ pre-selects all the macros that
     ‘autoheader’, ‘automake’, ‘autoreconf’, etc., trace, so that
     running ‘m4’ is not needed to trace them: the cache suffices.  This
     results in a huge speed-up.


   Finally, ‘autom4te’ introduces the concept of “Autom4te libraries”.
They consists in a powerful yet extremely simple feature: sets of
combined command line arguments:

‘--language=LANGUAGE’
‘-l LANGUAGE’
     Use the LANGUAGE Autom4te library.  Current languages include:

     ‘M4sugar’
          create M4sugar output.

     ‘M4sh’
          create M4sh executable shell scripts.

     ‘Autotest’
          create Autotest executable test suites.

     ‘Autoconf-without-aclocal-m4’
          create Autoconf executable configure scripts without reading
          ‘aclocal.m4’.

     ‘Autoconf’
          create Autoconf executable configure scripts.  This language
          inherits all the characteristics of
          ‘Autoconf-without-aclocal-m4’ and additionally reads
          ‘aclocal.m4’.

‘--prepend-include=DIR’
‘-B DIR’
     Prepend directory DIR to the search path.  This is used to include
     the language-specific files before any third-party macros.

   As an example, if Autoconf is installed in its default location,
‘/usr/local’, the command ‘autom4te -l m4sugar foo.m4’ is strictly
equivalent to the command:

     autom4te --prepend-include /usr/local/share/autoconf \
       m4sugar/m4sugar.m4f foo.m4

Recursive expansion applies here: the command ‘autom4te -l m4sh foo.m4’
is the same as ‘autom4te --language M4sugar m4sugar/m4sh.m4f foo.m4’,
i.e.:

     autom4te --prepend-include /usr/local/share/autoconf \
       m4sugar/m4sugar.m4f m4sugar/m4sh.m4f --mode 777 foo.m4

The definition of the languages is stored in ‘autom4te.cfg’.