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