- preg_replace: documentation ( source)
<?php
// Everything you enter here will be executed by our servers. Try it!
$content = "url('../../toto.jpg');";
$content = preg_replace('/url\(("|\')?\.\//', 'url(\\1', $content);
$content = preg_replace('/url\(("|\')?(?!(\'|"|)http)(?!(\'|"|)data)([^\/])/', 'url(\\1'
. $dirnameCss . '/\\4', $content);
echo $content;