(autoconf.info)Versions

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3.7 Version Numbers in 'configure'
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The following macros manage version numbers for 'configure' scripts.
Using them is optional.

 -- Macro: AC_PREREQ (VERSION)
     Ensure that a recent enough version of Autoconf is being used.  If
     the version of Autoconf being used to create 'configure' is earlier
     than VERSION, print an error message on the standard error output
     and do not create 'configure'.  For example:

          AC_PREREQ(1.8)

     This macro is useful if your 'configure.in' relies on non-obvious
     behavior that changed between Autoconf releases.  If it merely
     needs recently added macros, then 'AC_PREREQ' is less useful,
     because the 'autoconf' program already tells the user which macros
     are not found.  The same thing happens if 'configure.in' is
     processed by a version of Autoconf older than when 'AC_PREREQ' was
     added.

 -- Macro: AC_REVISION (REVISION-INFO)
     Copy revision stamp REVISION-INFO into the 'configure' script, with
     any dollar signs or double-quotes removed.  This macro lets you put
     a revision stamp from 'configure.in' into 'configure' without RCS
     or CVS changing it when you check in 'configure'.  That way, you
     can determine easily which revision of 'configure.in' a particular
     'configure' corresponds to.

     It is a good idea to call this macro before 'AC_INIT' so that the
     revision number is near the top of both 'configure.in' and
     'configure'.  To support doing that, the 'AC_REVISION' output
     begins with '#! /bin/sh', like the normal start of a 'configure'
     script does.

     For example, this line in 'configure.in':

          AC_REVISION($Revision: 1.30 $)dnl

     produces this in 'configure':

          #! /bin/sh
          # From configure.in Revision: 1.30