Adding and Deleting Users on CentOS 8: How To Guide

Linux is a multi-user operating system. Having proper knowledge of user management is crucial to proper system administration. If you are configuring a fresh Linux server, adding and deleting various users is usually one of the first things you have to do. This guide outlines the steps of adding and deleting users on CentOS 8.

Prerequisites

Creating and deleting users on CentOS requires you to work with a user with higher privilege. In Linux, the root user has the highest privilege. However, it’s generally safer to perform such changes with a non-root user with sudo privilege. In any case, the system administrator should be the one managing the user accounts on the system.

User Management

1)  Adding a user

First, have a look at how to create a new user. For demonstration, we will be using the username random_user. The following command will create a new basic user random_user:

Although the user is created, there’s no login credential configured. The next command will set a password to log in to the user:

The user is now ready to be accessed.

2)  Deleting a user

If the user account is no longer necessary, then it’s safe to delete it from the system. Depending on whether the data from the target user’s home directory is to be retained, there are two ways of deleting the user. If you want to keep the user’s home directory data intact, then run the following command:

If the user’s home directory data isn’t needed, then we can delete it as well. Just add the -r flag with the previous command:

After running either of the commands, the user will automatically be removed from any group. If another user with the same name is added later, all the permissions and group assignments have to be re-done.

User Permission

1)  Granting sudo privilege

By default, users can’t perform administrative tasks on CentOS. It’s gated only for the root and sudo-permitted users that can use the sudo command to run command(s) with administrative privilege. The default method of managing sudo permission is the wheel group. It’s a built-in user group that grants any user from this group access to the sudo command. It also reduces the necessity of adding each user manually to the sudoers file.

First, try running a sudo command without having sudo access as the new user:

If we want the new user to be able to run sudo commands, add them to the wheel group:

Next, verify if the change was successful. Run the following command as the new user:

2)  Listing users in wheel

The wheel group grants administrative privileges to its users. Having a look at the wheel group will help to manage user permissions more effectively. First, we’ll be using the getent tool. It’s a tool to get entries from supported administrative databases (including group). The group database contains the data about various user groups in the system. List the users in wheel:

Another way to list group users is using the lid command. It’s a dedicated tool to print user or group info. To list the wheel users, run the following command:

User Group

In the previous section, we demonstrated how to add a user to the wheel group. In this section, we’ll have a look at various basic user group actions.

1)  Adding a new group

Groups are effective to organize and administer user accounts. A particular group is generally defined by its set of privileges over various parts of the system, for example, reading, writing, and executing permissions. Managing user groups is only limited to root or user(s) with sudo privilege.

The following command will add a new group to the system:

Each group in the system has a specific group ID, also known as GID. To create a new group with a specific GID, run the following command:

A system group is a special type of group that’s generally dedicated to special system operations. To create a new system group, run the following command:

2)  Adding a user to a group

To add a user to an existing user group, use the following command structure:

3)  Listing users from a group

There are a couple of ways to list users from a group. The first method is using the getent tool:

The next method is using the lid command:

4)  Removing a user from a group

If a user is no longer necessary, we can remove that user from the particular group. Generally, a user group is a way to manage various permissions across the system. In practical scenarios, this means that the user will lose certain permissions and privileges on the system. To remove a user from a specific user group, you need to run the following command:

5)  Removing a group

Just like we created a group, we can also delete a group. If a group has no longer any purpose, then it’s safe to remove the group from the system. If the group serves as the primary group of a specific user, then the group can’t be deleted. So, before deletion, ensure that all the users in the group are properly removed.

To remove a group, run the following command:

Final Thoughts

This guide demonstrates the basics of adding and deleting users on CentOS 8. It also demonstrates the basics of user group management. It’s simple yet important to get it right. You should have a good understanding of user management basics from the guide. Proper user management will grant users access to only the sections of the system to get their job done.

You can now move on to further configuring your CentOS server. Take a look at the following tutorials to help you:

• How To Install Linux, Apache, MySQL, PHP (LAMP) stack on CentOS 7
• How to Install MySQL on CentOS 7
• Installing Node.js on CentOS 8: a Complete Guide

Happy Computing!