How to List Users in your Ubuntu Shell

There are two types of users in Linux, system users created by default with the system and regular users created by the system administrator. There are different ways to get information about these users, and in this article, you will learn about how to list users on Ubuntu 20.04.

Users are stored in a text file on the system called passwd file. This file is located in the /etc directory.

In this file, you can find all the information about the users in the system.

Get the list of all users using /etc/passwd file

Local user information is stored in the /etc/passwd file. Each line in this file represents login information for a user.

A quick and accurate way to list all users of the system is to run the cat or less command on this file. Please, open the terminal from the main menu and run

less /etc/passwd

You will get a screen output similar to this:

root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin 

As you can see in the output above, each line has seven delimited fields containing the following information:

1. User name
2. Encrypted password (Keep in mind that "x" means that the password is stored in the /etc/shadow file)
3. User Identification Number (UID)
4. User Group Identification Number (GID)
5. Full user name (GECOS)
6. User home directory
7. Login shell (default is /bin/bash)

List the users of the system without more information

This information is quite complete but may be unnecessary in many cases. If you want to show the names of the users without more, you can run

cut -d: -f1 /etc/passwd

Sample Output:

systemd-timesync
systemd-network
systemd-resolve
messagebus
rtkit
systemd-coredump
dnsmasq
uuidd
geoclue
avahi-autoipd
usbmux
saned
colord
speech-dispatcher
nm-openvpn
pulse
avahi
hplip
lightdm

Now you only have the usernames, and the information is much easier to understand.

Check if a user exists in the system

Now that we know how to list all the users and show all the information about them. It's time to check if a user exists in our Ubuntu. To do this, we can filter the list of users thanks to the grep command.

cat /etc/passwd | grep [username]

If the previous command's execution does not produce any screen output, then the user does not exist. If you do see the information, then it does.

Listing users in Ubuntu 20.04 using the getent command

Another way to list users on Ubuntu 20.04 and other Linux distributions is by using the getent command

The getent command displays entries from databases supported by the Name Service Switch libraries, which are configured in /etc/nsswitch.conf

So, it is very simple to use

getent passwd

And you will get the same screen output as in the first example.

Even though the output on the screen is the same, we prefer to use this tool instead of working directly with the passwd file.

Now you know how to get users information in your Ubuntu Shell and the process is quite simple.