In some cases, we need to change the username of the system or the user id (UID) of the system or both. In Linux there are lot configurations depends on user id like permissions. By using the command usermod you can change the username of your system. After changing the Username of UID the changes will affect systemwide. In this tutorial, you will learn how to change or rename username and UID in Linux.

Source: LXer – How to Change or Rename Username and UID in Linux