How do I list all users with root?

On a linux box, how do I list all users that have root priveleges (and even better, all users in general along with if they have root or not)?

Solution 1:

Don't forget to change the root password. If any user has UID 0 besides root, they shouldn't. Bad idea. To check:

grep 'x:0:' /etc/passwd

Again, you shouldn't do this but to check if the user is a member of the root group:

grep root /etc/group

To see if anyone can execute commands as root, check sudoers:

cat /etc/sudoers

To check for SUID bit, which allows programs to be executed with root privileges:

find / -perm -04000

Solution 2:

To see who is UID 0:

getent passwd 0

To see who is in groups root, wheel adm and admin:

getent group root wheel adm admin

To list all users and the groups they are members of:

getent passwd | cut -d : -f 1 | xargs groups

Solution 3:

Pure root is user id "0".

All the users in the system are in the /etc/passwd file:

less /etc/passwd

Those who are root have "0" as the user id, which is the 3rd column. Those with "0" as the group (4th column) may also have some root privileges.

Next, you'll want to look at the groups, and see who is an additional member of the "root" or "wheel" or "admin" groups:

less /etc/group

Users listed in those groups could have some root privileges, especially via the "sudo" command.

The final thing you will want to check is the "sudo" config and see who is listed as having authorisation to run this command. This file itself is well documented so I won't reproduce it here:

less /etc/sudoers

That covers the main areas of who could have root access.