3.4.4. Modifying User Settings

When a user already exists and you need to specify any of the options now, use the usermod command. The logic of using usermod is identical to useradd as well as its syntax:
usermod option(s) username
If you need to change the user's user name, use the -l option with the new user name (or login).

Example 3.10. Changing User's Login

~]# usermod -l "emily-smith" emily
The -l option changes the name of the user from the login emily to the new login, emily-smith. Nothing else is changed. In particular, emily's home directory name (/home/emily) remains the same unless it is changed manually to reflect the new user name.
In a similar way you can change the user's UID or user's home directory. See the example below:

Note

Find all files owned by the specified UID in system and change their owner. Do the same for Access Control List (ACL) referring to the UID. It is recommended to check there are no running processes as they keep running with the old UID.

Example 3.11. Changing User's UID and Home Directory

~]# usermod -a -u 699 -d /home/dir_2 robert
The command with -a -u and -d options changes the settings of user robert. Now, his ID is 699 instead of 501, and his home directory is no longer /home/robert but /home/dir_2.
With the usermod command you can also move the content of the user's home directory to a new location, or lock the account by locking its password.

Example 3.12. Changing User's

~]# usermod -m -d /home/jane -L jane
In this sample command, the -m and -d options used together move the content of jane's home directory to the /home/dir_3 directory. The -L option locks the access to jane's account by locking its password.
For the whole list of options to be used with the usermod command, see the usermod(8) man page or run usermod --help on the command line.