$re = '/^(?:uid=(?<uid>\d{6}),)?ou=(?<ou>\d{6}),dc=placetel,dc=de$/m';
$str = 'ou=200000,dc=placetel,dc=de
uid=231001,ou=200000,dc=placetel,dc=de
uid=231001,uid=231001,ou=200000,dc=placetel,dc=de
dc=placetel,dc=de
ou=200000,dc=placetel,dc=com
cn=admin,dc=placetel,dc=de';
preg_match_all($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