--- /dev/null
+#!/bin/sh
+set -e
+destdir="$1"; shift
+for f in "$@"; do install -m 644 -o root "$f" "$destdir/$f:new"; done
+cd "$destdir"
+for f in "$@"; do
+ if ! test -f "$f"; then
+ echo installing new "$destdir/$f"
+ mv -f "$f:new" "$f"
+ fi
+done