How To Add and Delete Users on CentOS 8
Prerequisites
This tutorial assumes you are logged into a CentOS 8 server with a non-root sudo-enabled user. If you are logged in as root instead, you can drop the sudo portion of all the following commands, but they will work either way.
Adding Users
Throughout this tutorial we will be working with the user tony. Please susbtitute with the username of your choice.
You can add a new user by typing:
$ sudo adduser tony
Next, you’ll need to give your user a password so that they can log in. To do so, use the passwd command:
$ sudo passwd tony
You will be prompted to type in the password twice to confirm it. Now your new user is set up and ready for use!
Granting Sudo Privileges to a User
If your new user should have the ability to execute commands with root (administrative) privileges, you will need to give them access to sudo.
We can do this by adding the user to the wheel group (which gives sudo access to all of its members by default).
Use the usermod command to add your user to the wheel group:
$ sudo usermod -aG wheel tony
Now your new user is able to execute commands with administrative privileges. To do so, append sudo ahead of the command that you want to execute as an administrator:
$ sudo some_command
You will be prompted to enter the password of the your user account (not the root password). Once the correct password has been submitted, the command you entered will be executed with root privileges.
Managing Users with Sudo Privileges
While you can add and remove users from a group with usermod, the command doesn’t have a way to show which users are members of a group.
To see which users are part of the wheel group (and thus have sudo privileges), you can use the lid command. lid is normally used to show which groups a user belongs to, but with the -g flag, you can reverse it and show which users belong in a group:
$ sudo lid -g wheel
Output
centos(uid=1000)
tony(uid=1001)
The output will show you the usernames and UIDs that are associated with the group. This is a good way of confirming that your previous commands were successful, and that the user has the privileges that they need.
Deleting Users
If you have a user account that you no longer need, it’s best to delete it.
To delete the user without deleting any of their files, use the userdel command:
$ sudo userdel tony
If you want to delete the user’s home directory along with their account, add the -r flag to userdel:
$ sudo userdel -r tony
With either command, the user will automatically be removed from any groups that they were added to, including the wheel group if applicable. If you later add another user with the same name, they will have to be added to the wheel group again to gain sudo access.