t/ax/is_newest

#! /bin/sh
# Copyright (C) 2012-2018 Free Software Foundation, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

# Usage: is_newest FILE FILES
# Fail if any file in FILES is newer than FILE, and print the list of
# such files on the standard error.  Resolve ties in favor of FILE.

# NOTE: keep this file Bourne-compatible, for the sake of systems with
#       non-POSIX /bin/sh (like Solaris).

set -u

me=is_newest

if test $# -lt 2; then
  echo "$me: too few arguments" >&2
  exit 2
fi

file=$1; shift
newer_files=`find "$@" -prune -newer "$file"` || exit $?

if test -n "$newer_files"; then
  echo "$me: these files are newer than '$file':" >&2
  for f in $newer_files; do echo "* $f" >&2; done
  exit 1
fi

exit 0