First edit the hostname file by typing:

sudo vi /etc/hostname

Delete the line that you see in the file so it our case we deleted:

localhost.localdomain

Now  enter your hostname, in our case we called it darrens centos.

 

We then typed

esc wq!

to write and save the file.

 

We then restart the machine by typing

sudo init 6

When the machine has re-booted type in

hostname

to see the new hostname.

A video tutorial can be found here: