AC_ARG

Example

configure.ac

AC_INIT([FULL-PACKAGE-NAME], [VERSION], [BUG-REPORT-ADDRESS])

AC_CONFIG_SRCDIR([main.c])
AC_CONFIG_HEADERS([config.h])
AC_CONFIG_FILES([Makefile])

AC_PROG_CC

AC_ARG_VAR(VAR_TQ84, [The description for variable VAR_TQ84])

AM_INIT_AUTOMAKE([foreign])

AC_OUTPUT

Github repository about-GNU-Build-System, path: /examples/AC_ARG_VAR/configure.ac

Makefile.am

bin_PROGRAMS       = ac_arg_var
ac_arg_var_SOURCES = main.c

Github repository about-GNU-Build-System, path: /examples/AC_ARG_VAR/Makefile.am

main.c

#include <stdio.h>

int main() {
  printf("AC_ARG_VAR\n");
}

Github repository about-GNU-Build-System, path: /examples/AC_ARG_VAR/main.c

Run

autoreconf --install

This creates a ./configure script.

Since configure.ac uses the AC_ARG_VAR(VAR_TQ84, [The description…]) macro, ./configure --help now shows, among others:

Some influential environment variables:
  …
  VAR_TQ84    The description for variable VAR_TQ84

./configure can no invoked, for example, with one of the following three:

VAR_TQ84=foo ./configure
./configure VAR_TQ84=bar
./configure

After invoking, the variable is accordingly set in the Makefile:

grep VAR_TQ84 Makefile

AC_ARG_VAR

Example

configure.ac

Makefile.am

main.c

See also