Computer name is normally given during the OS installing phases. But you could easily change the computer name with a simple GUI tool which is there in Ubuntu by default.There is a command line tool as well if you are so particular.GUI tool is simple and easy to use.Here is a step by step guide on how to change the computer name.

Using GUI

• Go to System -> Administration -> Networking

• Network settings

       General Tab -> Host Settings -> Hostname: Specify the computer name 

• save changes and restart your computer.

Using command line

• Goto terminal and type the following

          gksudo gedit /etc/hostname

• Change your hostname Also take a look at /etc/hosts. And change your old name to your new one too.

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