$re = '/\[[^][]*]|"([^"]*)"|\S+/m';
$str = '1.2.3.4 - - [02/Oct/2021:06:07:08 +0300 - -] 200 "GET /index.php HTTP/2.0" 6620 "https://l.instagram.com/" "Mozilla/5.0 (Linux; Android 9; SM-N950F) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.77 Mobile Safari/537.36" "-"
';
preg_match_all($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