xz/m4/posix-shell.m4

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dnl SPDX-License-Identifier: FSFULLR
# Find a POSIX-conforming shell.
# Copyright (C) 2007-2008 Free Software Foundation, Inc.
# This file is free software; the Free Software Foundation
# gives unlimited permission to copy and/or distribute it,
# with or without modifications, as long as this notice is preserved.
# Written by Paul Eggert.
# If a POSIX-conforming shell can be found, set POSIX_SHELL and
# PREFERABLY_POSIX_SHELL to it. If not, set POSIX_SHELL to the
# empty string and PREFERABLY_POSIX_SHELL to '/bin/sh'.
AC_DEFUN([gl_POSIX_SHELL],
[
AC_CACHE_CHECK([for a shell that conforms to POSIX], [gl_cv_posix_shell],
[gl_test_posix_shell_script='
func_return () {
(exit [$]1)
}
func_success () {
func_return 0
}
func_failure () {
func_return 1
}
func_ret_success () {
return 0
}
func_ret_failure () {
return 1
}
subshell_umask_sanity () {
(umask 22; (umask 0); test $(umask) -eq 22)
}
test "[$](echo foo)" = foo &&
func_success &&
! func_failure &&
func_ret_success &&
! func_ret_failure &&
(set x && func_ret_success y && test x = "[$]1") &&
subshell_umask_sanity
'
for gl_cv_posix_shell in \
"$CONFIG_SHELL" "$SHELL" /bin/sh /bin/bash /bin/ksh /bin/sh5 no; do
case $gl_cv_posix_shell in
/*)
"$gl_cv_posix_shell" -c "$gl_test_posix_shell_script" 2>/dev/null \
&& break;;
esac
done])
if test "$gl_cv_posix_shell" != no; then
POSIX_SHELL=$gl_cv_posix_shell
PREFERABLY_POSIX_SHELL=$POSIX_SHELL
else
POSIX_SHELL=
PREFERABLY_POSIX_SHELL=/bin/sh
fi
AC_SUBST([POSIX_SHELL])
AC_SUBST([PREFERABLY_POSIX_SHELL])
])