$re = '~^((\d|\*(/\d{1,2})?)\s){5}http://www.\S+/.+doing_wp_cron\s>/dev/null\s2>&1$~m';
$str = '*/30 * * * * http://www.testing.com/wp-cron.php?doing_wp_cron >/dev/null 2>&1
0 * * * * http://www.foo.test/bar.php?doing_wp_cron >/dev/null 2>&1
0 * * * * http://www.a.test/b.php?doing_wp_cron >/dev/null 2>&1
';
preg_match_all($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