$re = '/[GET|POST]\s(?<URL>.+(cashAccountOpenings\/v[0-9]|(?=\?)|((?=\/\s)|(?=\s)))).*(HTTP)/m';
$str = 'GET /gw/api/aaa/v1/ HTTP - to return /gw/api/aaa/v1
GET /gw/api/abc/v3 HTTP - to return /gw/api/abc/v3
POST /gw/api/cba/ HTTP - to return /gw/api/cba
POST /gw/transactions/swaggers/v2 HTTP - to return /gw/transactions/swaggers/v2
POST /gw/api/swaggers/v1/asd?dssa HTTP - to return /gw/api/swaggers/v1/asd
POST /api/swaggers/ HTTP - to return /api/swaggers
GET /api/cashAccountOpenings/v3/sadsa-123312-1312 HTTP - to return /api/cashAccountOpenings/v3';
preg_match_all($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