If you manage Linux systems, you’ve probably granted users special privileges at some point. Maybe you gave a teammate temporary access to install software. Or maybe you set up a new developer with administrative rights for testing.
The problem? It’s easy to forget who still has those privileges. Over time, this can become a security risk. That’s why it’s important to know exactly who has sudo access on your system — and remove it when it’s no longer needed.
In this guide, we’ll break down what sudo users are, why they matter, and how to list them on your Linux or Unix-like system.
Table of Contents
What Are Sudo Users?
In Linux, not every user has full control over the system.
Regular users have limited permissions. But sometimes they need to perform administrative tasks, like installing software or modifying system settings.
That’s where sudo comes in.
- sudo stands for “superuser do.”
- It allows regular users to run commands as the root user (administrator).
- Membership in certain groups, like
sudoorwheel, determines who gets this power.
Think of it as a special key that lets users open locked doors — but only when necessary.
Step 1: List All Users
Before checking who has sudo access, it’s helpful to see all the users on the system.
Run this command:
awk -F':' '{ print $1}' /etc/passwd
Or simply use:
See also: Mastering the Linux Command Line — Your Complete Free Training Guide
compgen -u
Both commands will print a list of usernames on your machine. But remember, not all of these are sudo users.
Step 2: Find Sudo Users with getent
On most Linux distributions, members of the sudo (or sometimes wheel) group have administrative privileges.
To see who’s in that group, run:
getent group sudo
Example output:
sudo:x:27:howtouselinux,tocao
Here’s what it means:
sudo→ the group name.x→ placeholder for a group password (not used today).27→ group ID.howtouselinux,tocao→ users who belong to the sudo group.
So in this case, both howtouselinux and tocao have sudo privileges.
Get a Cleaner Output
If you only want the usernames:
getent group sudo | cut -d: -f4
This command trims the output and shows only:
howtouselinux,tocao
Step 3: Check /etc/group File
Another way to identify sudo users is by looking directly at the /etc/group file.
cat /etc/group | grep '^sudo:'
Example output:
sudo:x:27:howtouselinux,tocao
Same story — these users are members of the sudo group.
Step 4: Verify a Specific User’s Access
Sometimes, you only need to check if one user has sudo privileges.
Run:
sudo -l -U username
For example:
sudo -l -U tocao
If the output shows they can run (ALL : ALL) ALL, it means they can run any command with sudo.
If the output instead says:
User tocao is not allowed to run sudo on ubuntuserver.
Then that user is just a regular account without elevated rights.
Quick Check with sudo -nv
Here’s another trick. Run:
sudo -nv
- If the command prints nothing, the user has sudo access.
- If you see an error message, the user does not.
Why This Matters
Periodically checking sudo users is good practice for every Linux admin.
- It helps prevent forgotten accounts with lingering privileges.
- It keeps your system secure by ensuring only trusted users have access.
- It gives you a clear view of who can perform administrative tasks.
FAQs
Q: What are sudo users in Linux?
They’re regular users who can temporarily elevate their privileges using the sudo command.
Q: How do I list all sudo users?
Check the sudo group with:
cat /etc/group | grep '^sudo:'
Q: Can I use sudo -l to find all sudo users?
No — that’s only for checking one user at a time.
Q: Why should I review sudo users?
Because forgotten privileges can pose security risks. Regular audits keep your system safe.
Q: Does this work on Unix-like systems other than Linux?
Yes. The commands are very similar on macOS, FreeBSD, and other Unix variants.
Final Thoughts
Managing sudo access isn’t just about convenience — it’s about security. By regularly checking which users have these privileges, you reduce the risk of unwanted changes and keep your systems safer.
Next time you hand out sudo access for a quick task, don’t forget to circle back and review it later.
