PHP file

http://php.net/manual/en/function.file-exists.php
http://www.informit.com/articles/article.aspx?p=29664&seqNum=7
http://php.net/manual/en/function.stream-get-contents.php
http://php.net/manual/en/function.strpos.php
http://php.net/manual/en/function.str-replace.php