$re = '/(http:\/\/site.ru(\/)*(msk|spb|region)*\/page)/';
$str = 'http://site.ru/msk/page
http://site.ru/spb/page
http://site.ru/region/page
http://site.ru/page
http://site.ru/aasfa32page
http://site.ruaasfa32/page
http://site.ru/aasfa32/page
';
preg_match_all($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