A. We use the help of the command usermod .
- Completely logout from the current user. i.e. the user you want to change. Logout from GUI and virtual console if you have.
- Login to virtual console as root or as a sudo capable user but not the user you want to change
- usermod -l new_user_name old_user_name
- groupmod -n new_user_name old_user_name
- usermod -d /home/new_user_name -m new_user_name
- usermod -c “Your full new Real Name” new_user_name
In Lucid Lynx, the LTS version of Ubuntu released recently, you can do it graphically from About me and User accounts.