File: autoconf.info,  Node: autoscan Invocation,  Next: ifnames Invocation,  Prev: Writing Autoconf Input,  Up: Making configure Scripts

3.2 Using ‘autoscan’ to Create ‘configure.ac’
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The ‘autoscan’ program can help you create and/or maintain a
‘configure.ac’ file for a software package.  ‘autoscan’ examines source
files in the directory tree rooted at a directory given as a command
line argument, or the current directory if none is given.  It searches
the source files for common portability problems and creates a file
‘configure.scan’ which is a preliminary ‘configure.ac’ for that package,
and checks a possibly existing ‘configure.ac’ for completeness.

   When using ‘autoscan’ to create a ‘configure.ac’, you should manually
examine ‘configure.scan’ before renaming it to ‘configure.ac’; it
probably needs some adjustments.  Occasionally, ‘autoscan’ outputs a
macro in the wrong order relative to another macro, so that ‘autoconf’
produces a warning; you need to move such macros manually.  Also, if you
want the package to use a configuration header file, you must add a call
to ‘AC_CONFIG_HEADERS’ (*note Configuration Headers::).  You might also
have to change or add some ‘#if’ directives to your program in order to
make it work with Autoconf (*note ifnames Invocation::, for information
about a program that can help with that job).

   When using ‘autoscan’ to maintain a ‘configure.ac’, simply consider
adding its suggestions.  The file ‘autoscan.log’ contains detailed
information on why a macro is requested.

   ‘autoscan’ uses several data files (installed along with Autoconf) to
determine which macros to output when it finds particular symbols in a
package's source files.  These data files all have the same format: each
line consists of a symbol, one or more blanks, and the Autoconf macro to
output if that symbol is encountered.  Lines starting with ‘#’ are
comments.

   ‘autoscan’ 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’
     Print the names of the files it examines and the potentially
     interesting symbols it finds in them.  This output can be
     voluminous.

‘--debug’
‘-d’
     Don't remove temporary files.

‘--include=DIR’
‘-I DIR’
     Append DIR to the include path.  Multiple invocations accumulate.

‘--prepend-include=DIR’
‘-B DIR’
     Prepend DIR to the include path.  Multiple invocations accumulate.