File: autoconf.info,  Node: autoupdate Invocation,  Next: Obsolete Macros,  Prev: acconfig Header,  Up: Obsolete Constructs

18.3 Using ‘autoupdate’ to Modernize ‘configure.ac’
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The ‘autoupdate’ program updates a ‘configure.ac’ file that calls
Autoconf macros by their old names to use the current macro names.  In
version 2 of Autoconf, most of the macros were renamed to use a more
uniform and descriptive naming scheme.  *Note Macro Names::, for a
description of the new scheme.  Although the old names still work (*note
Obsolete Macros::, for a list of the old macros and the corresponding
new names), you can make your ‘configure.ac’ files more readable and
make it easier to use the current Autoconf documentation if you update
them to use the new macro names.

   If given no arguments, ‘autoupdate’ updates ‘configure.ac’, backing
up the original version with the suffix ‘~’ (or the value of the
environment variable ‘SIMPLE_BACKUP_SUFFIX’, if that is set).  If you
give ‘autoupdate’ an argument, it reads that file instead of
‘configure.ac’ and writes the updated file to the standard output.

‘autoupdate’ accepts the following 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.

‘--force’
‘-f’
     Force the update even if the file has not changed.  Disregard the
     cache.

‘--include=DIR’
‘-I DIR’
     Also look for input files in DIR.  Multiple invocations accumulate.
     Directories are browsed from last to first.

‘--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.