#!/bin/sh

if [ $# -lt 3 ]; then
echo "
usage:

replace_in_tree <to_be_replaced> <replacement> '<filematcher>'
replaces the string "to_be_replaced" with "replacement"
from the current directory downwards the filetree
in files matching filematcher, e.g. '*' or '*.html'

example:

replace_in_tree 'Author: Bill Gates' 'Author: Larry Wall' '*.html'
"

exit
fi

find . -name "$3" -type f | xargs -n 255 perl -pi.bak -e 's/\Q$1\E/$2/g'