$re = '/^((?!rou\w+(\/\w+){2,}).)*$/m';
$str = '/fajwe/conv_1/routing/apwfe/afjwepfj
/fajwe/conv_2/routing/apwfe
/fajwe/conv_2/routing
/fajwe/conv_3/routing/apwfe/afjwepfj/awef
/fajwe/conv_4/routing/apwfe/afjwepfj/awef/0o09';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php