ifnames - Extract CPP conditionals from a set of files
ifnames [OPTION] ... [FILE] ...
Scan all of the C source FILES (or the standard input, if none are
given) and write to the standard output a sorted list of all the
identifiers that appear in those files in ‘#if’, ‘#elif’, ‘#ifdef’, or
‘#ifndef’ directives. Print each identifier on a line, followed by a
space-separated list of the files in which that identifier occurs.
print this help, then exit
print version number, then exit
Written by David J. MacKenzie and Paul Eggert.
Report bugs to <firstname.lastname@example.org>.
Copyright © 2003 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is
NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
autoconf(1), automake(1), autoreconf(1), autoupdate(1), autoheader(1),
autoscan(1), config.guess(1), config.sub(1), ifnames(1), libtool(1).
The full documentation for ifnames is maintained as a Texinfo manual.
If the info and ifnames programs are properly installed at your site,
should give you access to the complete manual.