$re = '/([\w+\-]){6,}/';
$str = '" 3 89 -90/ 900407-2"
" 3 9 -90/ 900407-1"
" 89 -9011/ 800408"
';
preg_match_all($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