You might run into a situation that requires you to change your computer name, either because you need it to meet a naming scheme or you’re just bored with it and want something better. By following these steps, you’ll give your computer a new identity in no time.

  1. Open a terminal window.
  2. Input the following command and hit Enter:
    gksudo gedit /etc/hostname (for linux desktop with GEdit)
    or
    sudo vi /etc/hostname (for linux server with vi editor)
  3. When prompted, enter the administrator password and click the OK button.
  4. The hostname file will open, displaying the current computer name. Replace the current computer name with the desired new name.
  5. Click Save.
  6. Close all open windows and restart your system.

After your system has restarted, it will have the new computer name.

Sumber :  http://www.tech-recipes.com/rx/2732/ubuntu_how_to_change_computer_name/