$re = '/(?P<before>(?:(?!\[download="[^"]*" type="[^"]*"\]).)*)\[download="(?P<download>[^"]*)" type="(?P<type>[^"]*)"\](?P<after>(?:(?!\[download="[^"]*" type="[^"]*"\]).)*)/';
$str = 'text here [download="PDC" type="A"] and the text continues [download="PDS" type="B"] and more text yet again, more shotcodes might exist ...';
preg_match_all($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