$re = '/(?<=p)\d+|(?<=mim)\d+/';
$str = '3/1/1/10=p3 12/mim1=eth11
3/1/1/11=p4 12/mim3=eth11
3/1/1/1=p1 12/mim2=eth11
3/1/1/12=p5 13/mim1=eth11
3/1/1/13=p6 13/mim3=eth11
3/1/1/2=p2 13/mim2=eth11
8/mim1=eth11 3/1/2/5=p7
8/mim2=eth11 3/1/2/6=p8
3/1/2/11=p9 4/mim1=eth11';
preg_match_all($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