#!/bin/sh
# sediff [-pSTRIP] [SEDSCRIPT] {FILES...} - generate diff from sed execution

strip=0
case "$1" in
-p*)
	strip=${1#-p}
        shift
esac

expr=$1
shift

for file; do
	label=$file
        n=$strip
        while [ "$((n = n-1))" -ge 0 ]; do
	        label=${label#*/}
	done
	sed -e "$expr" "$file" |
        	diff -u --label "$label.orig" "$file" --label "$label" -
done