If you are trying to restart an Apache server running on Ubuntu, Linux Mint or any other Ubuntu derived distro, you will get an warning message that your Apache server does not contain a fully qualified domain name.

Restarting Apache
# sudo /etc/init.d/apache2 restart

Warning Message
* Restarting web server apache2
apache2: Could not reliably determine the server’s fully qualified domain name, using 127.0.1.1 for ServerName … waiting apache2: Could not reliably determine the server’s fully qualified domain name, using 127.0.1.1 for ServerName [ OK ]

To fix this annoying message, you need to set the hostname:

Set Hostname
# sudo hostname computername.domain.com

So, the next time you restart the Apache server:

Restart Apache
# sudo /etc/init.d/apache2 restart

There are no more warning messages.

No More Messages
* Restarting web server apache2
… waiting                                                              [ OK ]