谁在论坛上？

Warning: Undefined variable $user in /home/guagua/wwwroot/dcms.myredirect.us/forum/on-forum.php on line 12

Warning: Trying to access array offset on value of type null in /home/guagua/wwwroot/dcms.myredirect.us/forum/on-forum.php on line 12
谁在论坛上？