case 'nick':
    if(count($params) == 0){
      $srv->send($uid, 'Error: Nick missing.');
      return false;
    }
    $nick_new = $params[0];
    $nick_old = get_nick($uid);
    for($i = 0;$i <= $srv->active_clients;$i++){
      if($nick_new == get_nick($i)){
	$srv->send($uid, 'Error: Nick already in use.');
	return false;
      }
    }
    set_nick($uid, $nick_new);
    if(empty($nick_old)){
      global_send('['.$nick_new.'] joined the chat.');
      $srv->send($uid, 'You have joined the chat as ['.$nick_new.'].');
      echo '['.$srv->get_addr($uid).'] is ['.$nick_new."]\n";
      return true;
    }
    global_send('['.$nick_old.'] is now ['.$nick_new.']');
    $srv->send($uid, 'Your nick was changed to ['.$nick_new.']');
    echo '['.$srv->get_addr($uid).'] is now ['.$nick_new."\n";
    break;