#!/bin/sh

[ -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
    U=-u
    [ "${f##*/}" == "ChangeLog$2" ] && U=-U0
    diff ${U} $f `echo $f | sed s/$2\$//`
done