5.12 UNIX Variants

The following macros check for certain operating systems that need special treatment for some programs, due to exceptional oddities in their header files or libraries. These macros are warts; they will be replaced by a more systematic approach, based on the functions they make available or the environments they provide.

Macro: AC_AIX

If on AIX, define _ALL_SOURCE. Allows the use of some BSD functions. Should be called before any macros that run the C compiler.

Macro: AC_ISC_POSIX

If on a POSIXized ISC UNIX, define _POSIX_SOURCE and add `-posix' (for the GNU C compiler) or `-Xp' (for other C compilers) to output variable CC. This allows the use of POSIX facilities. Must be called after AC_PROG_CC and before any other macros that run the C compiler.

Macro: AC_MINIX

If on Minix, define _MINIX and _POSIX_SOURCE and define _POSIX_1_SOURCE to be 2. This allows the use of POSIX facilities. Should be called before any macros that run the C compiler.