gpt-undefines Generates a list of preprocessor macros that are not
defined internally in the source code. Macros that are defined in the
header files listed during gpt-undefines's invocation will also be
Use PATH as the directory containing the source code. Source code in
the entire directory tree will be scanned. Default PATH is the
directory gpt-undefines was invoked in.
Prints the list out in a format that can be pasted into an installable
Do not count commented out undefines as a define. This technique is
used by autoconf to indicate a negative test result. Example:
/* #undef HAVE_TCP_FASTACK */
Managing Autoconf defines.
By default the defines tested for by the configure script are stored
in a file called config.h. This file should never be installed. to
add autoconf defines to config.h simply add the define in the
following format to the file acconfig.h:
acconfig.h is tranformed into a config.h.in by the script
autoheader. Then the configure script transform it into config.h.
A problem occurs when the autoconf defines are used in installed
header files. In this case the defines should be put in an
installable header file using the following format: