Trevor Williams/DigitalVision via Getty Follow ZDNET: Add us as a preferred source on Google. The usermod command is short for user modification, and, as the name implies, allows you to modify various aspects of a user account. For a Linux administrator, this command is crucial. For Linux users, the command most certainly comes in handy, especially given what it can do. Let's dive down this rabbit hole and see what's what with the Linux usermod command. 1. Change user details When you create a Linux user with the adduser command, you can include certain details to go along with the new user (such as full name, office and home phone numbers, and other information, which can be used as a description. After you've created the user, the only way to change or add such information is via the usermod command. Say, for instance, you want to add a comment for a user. To do that, you would issue the command: sudo usermod -c "INFORMATION" USER Also: 5 surprisingly productive things you can do with the Linux terminal Where INFORMATION is what you want to add, and USER is the user account you want to change. This can be handy if you have two users with the same first name and you want to differentiate them in their user information. 2. Change a username You can also change a username. Before you do this, know that it does not change the user's home directory name. So if I have the user sam and I want to change it to samantha, usermod is there to help me. Such a command would look like this: sudo usermod -l samantha sam The -l option is for the login name. 3. Rename a home directory After you change a username, you might also want to rename the user's home directory. Before you do this, you must ensure that the user is logged out; otherwise, it could wreak havoc on their account (or their data). You also need to make sure that the user's data is added to the new home directory (otherwise, the user winds up with an empty home). To change a directory name (and add the data), you would use a command like this (sticking with our sam/samantha example): sudo usermod -d /home/samantha -m sam The -d option sets the new home directory path, and the -m option moves the data. Also: There's a new coolest Linux distribution ready to wow you 4. Lock and unlock a user's account There may be times when you need to lock a user out of their account (and later allow them back in). This could be used for temporary employees or grounded children. To lock a user account, the command would be: sudo usermod -L USER Where USER is the username to which the lock applies. To unlock the account, you would issue the command: sudo usermod -U USER Where USER is the user account. 6. Change a user's account expiry date Did you know you can expire a user account in Linux? Let's say you have a temp employee whose contract ends on October 31, 2025. If you want to set the person's user account to expire on that date (instead of having to remember it when the date arrives), you can use the expiry feature of usermod like so: sudo usermod -e 2025-10-31 USER Where USER is the user account name. 7. Add a user to a group (or groups) I've had to use this feature so many times. For example, I use Docker a lot, and when I install it, I have to add users to the group (otherwise it won't work for them without using sudo, which can lead to security issues). You might have also created a group that will be used by several accounts to access a specific folder. Let's say you've created the editorial group and want to add sam to it. The command for that would be: sudo usermod -aG editorial sam Also: 7 Linux terminal basics every beginner should learn first - and why 8. Modify a user's home directory If you've renamed a user account, you'll notice their home directory is still listed as the original username. If you would like to rename the user's home directory (to avoid confusion), usermod has your back. Before you do this, however, it's important that you make sure the user is logged out of their account (otherwise, it could cause serious problems). To change the name of a user's home directory, the command would be: sudo usermod -d /home/NEWNAME OLDNAME Where NEWNAME is the new name for the directory and OLDNAME is the current name. 9. Change a user's shell Chances are pretty slim that you'll ever need to do this, but you can change a user's shell. Let's say you want to change samantha's shell from bash to zsh. To do that, you should first make sure the new shell is actually installed with the command: cat /etc/shells If zsh is listed, you can change it for samantha with the following command: sudo usermod -s /bin/SHELL samantha Want to follow my work? Add ZDNET as a trusted source on Google.