AC_SUBST

AC_SUBST writes a variable into the Makefile.

The following three snippets are equivalent:

AC_SUBST([VAR],[Value])

VAR=Value AC_SUBST([VAR])

AC_SUBST([VAR]) VAR=Value

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_SUBST(VAR_TQ84, 'tq84')

AM_INIT_AUTOMAKE([foreign])

AC_OUTPUT

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

Makefile.am

bin_PROGRAMS     = ac_subst
ac_subst_SOURCES = main.c

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

main.c

#include <stdio.h>
int main() {

  printf("AC_SUBST");

}

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

Run

autoreconf --install
./configure

The AC_SUBST(VAR_TQ84, 'tq84') macro in configure.ac declares the variable VAR_TQ84 with value tq84 in the Makefile:

grep VAR_TQ84 Makefile

AC_SUBST

Example

configure.ac

Makefile.am

main.c

See also