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Adding Users to the sudo Group in Linux

Benhcmark Administrator

09/09/2025

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How to Add a User to the Sudo Group in Linux: A Step-by-Step Guide

Properly managing user privileges is a cornerstone of Linux system administration. Instead of logging in directly as the all-powerful root user—a significant security risk—the best practice is to grant administrative privileges to a standard user account. This is accomplished using the sudo (superuser do) command, which allows a permitted user to execute commands as root or another user.

This guide will walk you through the essential steps to add a user to the sudo group, empowering them with the necessary administrative access in a secure and controlled manner.

Prerequisites

Before you begin, ensure you have access to the system’s terminal and are logged in as either:

• The root user.
• A user account that already has sudo privileges.

The Core Command: usermod

The primary tool for modifying a user account, including their group memberships, is the usermod command. We will use it with specific flags to add a user to the appropriate administrative group without removing them from any existing groups.

The critical flags are:

• -a (append): This adds the user to a new group. Without this flag, the user will be removed from all other groups not listed in the command.
• -G (groups): This specifies the group(s) to which you want to add the user.

Adding a User to Sudo on Debian and Ubuntu

On Debian, Ubuntu, and their derivatives (like Linux Mint), the group that grants sudo privileges is named sudo.

To add an existing user to this group, execute the following command in your terminal, replacing username with the actual name of the user:

sudo usermod -aG sudo username

For example, to grant sudo access to a user named alex, you would run:

sudo usermod -aG sudo alex

Adding a User to Sudo on CentOS, RHEL, and Fedora

On Red Hat Enterprise Linux (RHEL), CentOS, Fedora, and other RHEL-based distributions, the administrative group is traditionally named wheel.

The process is nearly identical, but you must specify the wheel group instead of sudo. Use this command, replacing username with the target user’s name:

sudo usermod -aG wheel username

For instance, to give a user named maria administrative rights on a CentOS server, the command would be:

sudo usermod -aG wheel maria

How to Verify Sudo Access

After running the usermod command, it’s important to verify that the user has been successfully added to the correct group. You can do this with the groups command.

Simply run the following, once again replacing username with the relevant user’s name:

groups username

The output will list all the groups the user belongs to. You should see either sudo or wheel in the list, depending on your Linux distribution.

For example, after adding alex to the sudo group, the output might look like this:
alex : alex sudo

Activating the New Privileges

This is a crucial final step that is often overlooked. For the new group membership to take effect, the user must log out and log back in again. Until they start a new session, their old permissions will remain active, and they will not be able to use sudo.

Once the user has logged back in, they can test their new privileges by running a simple command with sudo, such as updating the package list:

sudo apt update  # For Debian/Ubuntu

or

sudo dnf check-update # For RHEL/CentOS/Fedora

The system will prompt for their own user password, not the root password. If the command executes successfully, the user now has sudo access.

Security Best Practices for Sudo Management

Granting administrative access is a significant responsibility. Follow these principles to maintain system security:

1. Grant Privileges Sparingly: Only provide sudo access to users who absolutely require it for their roles. This is known as the principle of least privilege.
2. Use Strong Passwords: A user’s sudo access is only as secure as their account password. Enforce strong, unique passwords for all administrative users.
3. Audit Sudo Usage: All commands executed with sudo are logged, typically in files like /var/log/auth.log or /var/log/secure. Regularly reviewing these logs can help you detect unauthorized or suspicious activity.
4. Avoid Universal Root Access: For highly secure environments, consider using the visudo command to edit the /etc/sudoers file. This allows you to grant users permission to run only specific commands, rather than providing full root access.

Source: https://kifarunix.com/how-to-add-users-to-sudo-group-in-linux/