mv-if-diff

: mv-if-diff file1 file2
: move file1 to file2 if file1 and file2 are different.

if test $# -lt 2 ; then
	echo "usage:  $0 file1 file2"
	echo "move file1 to file2 if file1 and file2 are different."
	exit 1
fi
if cmp $1 $2 >/dev/null 2>&1; then
	echo "File $2 not changed."
	rm -f $1
else
	rm -f $2
	mv $1 $2
fi