Hello friends, My configure.ac is: AC_PREREQ(2.69) AC_INIT([mkbib], [2.1], [bnrj.rudra@xxxxxxxxx]) AC_CONFIG_AUX_DIR([build-aux]) AM_INIT_AUTOMAKE([1.9.6 dist-bzip2 subdir-objects foreign]) # Checks for programs. AC_PROG_CC AC_PROG_YACC #if test x"$YACC" != x"yes"; then # AC_MSG_ERROR([Please install bison before installing.]) #fi AC_PROG_LEX if test "x$LEX" != xflex; then AC_MSG_ERROR([Please install flex before installing.]) fi AC_CONFIG_MACRO_DIR([m4]) GNOME_DOC_INIT # Compiling sources with per-target flags requires AM_PROG_CC_C_O AM_PROG_CC_C_O AC_PROG_INSTALL #AC_PROG_LIBTOOL PKG_CHECK_MODULES(LIBSOUP, libsoup-2.4 >= 2.26) AC_SUBST(LIBSOUP_CFLAGS) AC_SUBST(LIBSOUP_LIBS) AM_PATH_GTK_3_0([3.4.0],,AC_MSG_ERROR([Gtk+ 3.0.0 or higher required.])) AC_CONFIG_HEADERS([config.h]) AC_CONFIG_FILES([ Makefile help/Makefile ]) AC_OUTPUT The problem is, while running ./configure built from this file, do check existence of YACC (as bison, when the 3 line following AC_PROG_YACC, it is showing unary error), but is not exiting once error is detected. As, the run, it shows: checking for bison... no checking for byacc... no checking that generated files are newer than configure... done configure: creating ./config.status config.status: creating Makefile config.status: creating help/Makefile config.status: creating config.h config.status: config.h is unchanged config.status: executing depfiles commands So, how can I make configure.ac to stop for missing bison ? _______________________________________________ Autoconf mailing list Autoconf@xxxxxxx https://lists.gnu.org/mailman/listinfo/autoconf