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-rwxr-xr-xwrite-ifchanged26
1 files changed, 26 insertions, 0 deletions
diff --git a/write-ifchanged b/write-ifchanged
new file mode 100755
index 0000000..bd702a8
--- /dev/null
+++ b/write-ifchanged
@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+# Copyright (C) 2015 Luke Shumaker
+# SPDX-License-Identifier: AGPL-3.0-or-later
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+outfile=$1
+tmpfile="$(dirname "$outfile")/.tmp.${outfile##*/}.tmp"
+
+cat > "$tmpfile" || exit $?
+if cmp -s "$tmpfile" "$outfile"; then
+ rm -f "$tmpfile" || :
+else
+ mv -f "$tmpfile" "$outfile"
+fi