Initial revision

diff --git a/m4/shell.m4 b/m4/shell.m4
new file mode 100644 (file)
index 0000000..784f0b7
--- /dev/null
+++ b/m4/shell.m4
@@ -0,0 +1,46 @@
+#serial 1
+
+# Check for a working (i.e. POSIX-compatible) shell.
+
+# Written by Paul Eggert <eggert@twinsun.com>,
+# from an idea suggested by Albert Chin-A-Young <china@thewrittenword.com>.
+
+AC_DEFUN(AC_PROG_SHELL,
+  [AC_MSG_CHECKING(for a POSIX-compliant shell)
+   AC_CACHE_VAL(ac_cv_path_shell,
+     [ac_cv_path_shell=no
+      IFS="${IFS=      }"; ac_save_ifs="$IFS"; IFS=":"
+      ac_dummy=/bin:/usr/bin:/usr/bin/posix:/usr/xpg4/bin:$PATH
+      for ac_dir in $ac_dummy; do
+       for ac_base in sh bash ksh sh5; do
+         case "$ac_dir" in
+         /*)
+           if ("$ac_dir/$ac_base" -c '
+
+                 # Test the noclobber option,
+                 # using the portable POSIX.2 syntax.
+                 set -C
+                 rm -f conftest.c || exit
+                 >conftest.c || exit
+                 >|conftest.c || exit
+                 !>conftest.c || exit
+
+               ') 2>/dev/null; then
+             ac_cv_path_shell="$ac_dir/$ac_base"
+             break
+           fi
+           ;;
+         esac
+       done
+       if test "$ac_cv_path_shell" != no; then
+         break
+       fi
+      done
+      IFS="$ac_save_ifs"])
+   AC_MSG_RESULT($ac_cv_path_shell)
+   SHELL=$ac_cv_path_shell
+   if test "$SHELL" = no; then
+     SHELL=/bin/sh
+     AC_MSG_WARN(Using $SHELL, even though it is not POSIX-compliant)
+   fi
+   AC_SUBST(SHELL)])