php modify variables in files

$filename ="bbbbbbb";

$dir = dirname(__FILE__);

$path = $dir."".DIRECTORY_SEPARATOR."config.php";

echo $path;

$contents = file_get_contents($path);

$contents = modify_ini_value($contents,"theme",$filename);

file_put_contents($path,$contents);

function modify_ini_value($content,$key,$replace){

$match = '/([ t]*)($'.$key.'s*=s*"?)(.*?)("?)(s*;s*$)/m';

return (preg_replace($match,"${1}${2}{$replace}${4}${5}",$content));

}