Here are all of the switches we can use for usermod followed by some examples of how to use them,
-c = We can add comment field for the useraccount.
-d = To modify the directory for any existing user account.
-e = Using this option we can make the account expiry in specific period.
-g = Change the primary group for a User.
-G = To add a supplementary groups.
-a = To add anyone of the group to a secondary group.
-l = To change the login name
-L = To lock the user account. This will lock the password so we cant use the account.
-m = moving the contents of the home directory from existing home dir to new dir.
-p = To Use un-encrypted password for the new password. (NOT Secured).
-s = Create a Specified shell for new accounts.
-u = Used to Assigned UID for the user account between 0 to 999.
-U = To unlock the user accounts. This will remove the password lock and allow us to use the user account.
Modify the home directory of a user
usermod -d /home/techshizz
Add a user to additional groups
usermod -G sudo,admins
Unlock a user account
usermod -U rich