List sudo or super users in Linux

Let us first list all users in the system. To do so, run:

$ awk -F':' '{ print $1}' /etc/passwd

Sample output from my Ubuntu system:

root

daemon

bin

sys

sync

games

man

lp

mail

news

uucp

proxy

www-data

backup

list

irc

gnats

nobody

systemd-timesync

systemd-network

systemd-resolve

systemd-bus-proxy

syslog

_apt

lxd

messagebus

uuidd

dnsmasq

sshd

sk

senthil

kumar

ostechnix

You can also use the following command to list all users:

$ compgen -u

Among all users, let us only find the sudo or super users in our Linux system.

$ grep '^sudo:.*$' /etc/group | cut -d: -f4

sk,ostechnix

Also, you can use “getent” command instead of “grep” to get the same result.

$ getent group sudo | cut -d: -f4

sk,ostechnix

As you see in the above output, “sk” and “ostechnix” are the sudo users in my system.

In the above examples, we listed all sudo users. You might want to know whether a certain user has sudo privilege or not.

To do so, run:

$ sudo -l -U sk

Sample output:

Matching Defaults entries for sk on ubuntuserver:

 env_reset, mail_badpass,

 secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin

User sk may run the following commands on ubuntuserver:

 (ALL : ALL) ALL

As you see, the user named “sk” can perform all commands. So, he is in the sudo group. Let us check another user.

$ sudo -l -U senthil

Sample output:

User senthil is not allowed to run sudo on ubuntuserver.

Oops! The user “senthil” is not allowed to run sudo, so he is just a normal user.

We can also find if an user has sudo access by running the following command:

$ sudo -nv

If you get nothing as output, the user still has sudo access.

If you see an output like below, then the user doesn’t has sudo access.

$ sudo -nv

Sorry, user senthil may not run sudo on ubuntuserver.