tools/mtime.sh: New file

1 files changed, 71 insertions, 0 deletions

diff --git a/tools/mtime.sh b/tools/mtime.sh
new file mode 100755
index 0000000..c2f9dfa
--- /dev/null
+++ b/tools/mtime.sh
@@ -0,0 +1,71 @@
+#!/bin/sh
+#
+# Utility to portably get a file's modification time
+#
+# Copyright (C) 2018, 2019  Patrick McDermott
+#
+# 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 3 of the License, 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 <http://www.gnu.org/licenses/>.
+
+set -u
+
+get_mtime()
+{
+	local file="${1}"
+	shift 1
+	local m=
+	local d=
+	local y=
+	local now_m=
+	local now_y=
+
+	read m d y <<-EOF
+		$(LC_ALL=POSIX ls -l "${file}" | cut -d ' ' -f 6-8)
+		EOF
+	case "${m}" in
+		'Jan')  m=1;; 'Feb')  m=2;; 'Mar')  m=3;; 'Apr')  m=4;;
+		'May')  m=5;; 'Jun')  m=6;; 'Jul')  m=7;; 'Aug')  m=8;;
+		'Sep')  m=9;; 'Oct') m=10;; 'Nov') m=11;; 'Dec') m=12;;
+	esac
+	case "${y}" in *':'*)
+		read now_m now_y <<-EOF
+			$(date '+%m %Y')
+			EOF
+		now_m="${now_m#0}"
+		if [ ${now_m} -ge ${m} ]; then
+			y=${now_y}
+		else
+			y=$((${now_y} - 1))
+		fi
+	esac
+
+	printf '%d-%02d-%02d\n' ${y} ${m} ${d}
+	return 0
+}
+
+usage()
+{
+	printf 'Usage: %s <file>\n' "${0}"
+}
+
+main()
+{
+	if [ ${#} -lt 1 ]; then
+		usage >&2
+		exit 1
+	fi
+
+	get_mtime "${1}"
+}
+
+main "${@}"