#!/bin/bash

[ -z "$1" -o -z "$2" ] && {
# usage
  echo "usage: $0 <directory> <diff-extension>" 1>&2
  exit 1
}

find $1 \( -name "*$2" -o -name ".*$2" \) -print |
while read f; do
	diff -u $f ${f%%$2}
done