How to update "user name" and "group name" in linux

Update user name.

First i will show the all users in the system using the command 
 "cat /etc/passwd".

Then the i am going to change user name "thamilnadu" to "bangalore" using the command  "sudo usermod -l new_user_name old_user_name".

Next i am going to display the changed user name.

Update the group name.


 First i will show all the groups in the sysytem using the command              "cat /etc/group".

Then i am going to change the group name "my_india" to "india" using the command "sudo groupmod -n new_group_name old_group_name".

Next i am going to display the changed group name