Changing User Attributes

The usermod command is used to change attributes of an existing user account.

Changing the Primary Group (-g)

This changes the user's primary group ID.

bash $ sudo usermod -g developers alice

Adding to Secondary Groups (-aG)

To add a user to secondary groups without removing them from their existing ones, you must use the -a (append) and -G (Groups) options together.

bash

Add user 'bob' to 'sysadmin' and 'web_ops' groups:

$ sudo usermod -aG sysadmin,web_ops bob

Changing the Username (-l)

This changes the login name of the user.

bash

Change jdoe's username to johnnyd

$ sudo usermod -l johnnyd jdoe

Note: Changing the username does not automatically rename the home directory. Use -d and -m to move and rename the home directory separately if needed.