The autoupdate program updates a configure.in 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. Although the old names still work , you can make your configure.in 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.in, 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.in__ and writes the updated file to the standard output.
autoupdate accepts the following options:
Print a summary of the command line options and exit.
Print the version number of Autoconf and exit.
Report processing steps.
Don't remove the temporary files.
Look for the installed macro files in directory dir. You can also set the AC_MACRODIR environment variable to a directory; this option overrides the environment variable.