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    By Dmitrii MaksimovDecember 18th 2020

    There are 2 types of users in Linux, system users that are 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 /etcdirectory.

    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.

    So, 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:

    • User name
    • Encrypted password (Keep in mind that "x" means that the password is stored in the /etc/shadow file)
    • User Identification Number (UID)
    • User Group Identification Number (GID)
    • Full user name (GECOS)
    • User home directory
    • 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 just 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 execution of the previous command does not produce any screen output, then the user does not exist. If you see his 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.

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