mohammad@mohammad:~$ sudo /etc/init.d/apache2 restart
[sudo] password for mohammad:
 * Restarting web server apache2                                                apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName
apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName
                                                                         [ OK ]