rpm-build/gendiff

#!/bin/sh

if [ -z "$1" -o -z "$2" ]; then
	echo "usage: ${0##*/} <directory> <diff-extension>" >&2
	exit 1
fi

if [ -n "$3" ]; then
	: ${SOURCEDIR:=`rpm --eval %_sourcedir`}
	>"$SOURCEDIR/$1-$3.patch"
fi

find "$1" -mindepth 1 \( -name "*$2" -o -name ".*$2" \) -print |
	while read fin; do
		fou=`echo "$fin" |sed -e "s/$2\$//"`
		[ -r "$fin" ] || fin="/dev/null"
		[ -r "$fou" ] || fou="/dev/null"
		if [ -n "$3" ]; then
			diff -u "$fin" "$fou" |
				tee -a "$SOURCEDIR/$1-$3.patch"
		else
			diff -u "$fin" "$fou"
		fi
	done