move-if-change

#!/bin/sh
# Like mv $1 $2, but if the files are the same, just delete $1.
# Status is 0 if $2 is changed, 1 otherwise.

if test -r "$2"; then
    if cmp -s "$1" "$2"; then
	echo >&2 "$2 is unchanged"
	rm -f "$1"
    else
	mv -f "$1" "$2"
    fi
else
    mv -f "$1" "$2"
fi