$re = '/\bS(?:-\d){2}(?:-\d{10}){2}-\d{9}(?:-\d{10}){2}(?:-\d){5}\b/m';
$str = 'The SID is S-1-9-1551374245-3853148685-361627209-2951783729-4075502353-0-0-0-0-3';
preg_match_all($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