autoconf: ifnames Invocation

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1 3.3 Using `ifnames' to List Conditionals
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1 `ifnames' can help you write `configure.ac' for a software package.  It
1 prints the identifiers that the package already uses in C preprocessor
1 conditionals.  If a package has already been set up to have some
1 portability, `ifnames' can thus help you figure out what its
1 `configure' needs to check for.  It may help fill in some gaps in a
1 `configure.ac' generated by `autoscan' (⇒autoscan Invocation).
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1    `ifnames' scans all of the C source files named on the command line
1 (or the standard input, if none are given) and writes to the standard
1 output a sorted list of all the identifiers that appear in those files
1 in `#if', `#elif', `#ifdef', or `#ifndef' directives.  It prints each
1 identifier on a line, followed by a space-separated list of the files
1 in which that identifier occurs.
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1 `ifnames' accepts the following options:
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1 `--help'
1 `-h'
1      Print a summary of the command line options and exit.
1 
1 `--version'
1 `-V'
1      Print the version number of Autoconf and exit.
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