Change Ubuntu Hostname (computer name)
Type the following command to edit /etc/hostname using nano or vi text editor:
sudo nano /etc/hostname
Delete the old name and setup new name.
Next Edit the /etc/hosts file:
sudo nano /etc/hosts
Replace any occurrence of the existing computer name with your new one. Reboot the system to changes take effect:
sudo reboot
Display the current Ubuntu hostname
$ hostname
change the Ubuntu server hostname without a system restart
Type the following commands:
$ sudo hostname new-server-name-here
Next edit the /etc/hostname file and update hostname:
$ sudo nano /etc/hostname
Finally, edit the /etc/hosts file and update the lines that reads your old-host-name:
$ sudo nano /etc/hosts