$re = '/(?!.*\bignore\b).*\bapp prod\b.*/m';
$str = '1. blah app prod blah blah
2. blah app prod blah ignore
3. blah app staging blah blah
4. blah app staging blah ignore
5. blah app prod blah blah blah ignore blah blah
6. blah blah';
preg_match_all($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