How to change hostname in ubuntu or debian

step 1

nano /etc/hostname

step 2

change in the name that you like

(old name)

step 3

(new name)

step 4

nano /etc/hosts

step 5

(old name)

step 6

(new name)

sudo service hostname restart

                                                  sudo  /etc/init.d/hostname restart

   sudo service networking restart