$re = '/^\d{4}/m';
$str = '0127,Central WM
0128,Central WM
0129,Central WM
0130,Central WM
089I,Inbound EWM
089O,Outbound EWM
089P,PSA in EWM
9988,Packstücke WM
CM01,CM01 in 1000
CM02,CM02 in 1000';
preg_match_all($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