Using `ifnames' to List Conditionals
====================================
`ifnames' can help when writing a `configure.in' for a software
package. It prints the identifiers that the package already uses in C
preprocessor conditionals. If a package has already been set up to
have some portability, this program can help you figure out what its
`configure' needs to check for. It may help fill in some gaps in a
`configure.in' generated by `autoscan' (Note:Invoking autoscan).
`ifnames' scans all of the C source files named on the command line
(or the standard input, if none are given) and writes to the standard
output a sorted list of all the identifiers that appear in those files
in `#if', `#elif', `#ifdef', or `#ifndef' directives. It prints each
identifier on a line, followed by a space-separated list of the files
in which that identifier occurs.
`ifnames' accepts the following options:
`--help'
`-h'
Print a summary of the command line options and exit.
`--macrodir=DIR'
`-m DIR'
Look for the Autoconf macro files in directory DIR instead of the
default installation directory. Only used to get the version
number. You can also set the `AC_MACRODIR' environment variable
to a directory; this option overrides the environment variable.
`--version'
Print the version number of Autoconf and exit.