> ## Content Index > Fetch the complete content index at: https://snubmonkey.com/llms.txt > Use this file to discover other available public pages before exploring further. # Managing Users. - URL: https://snubmonkey.com/managing-users/ - Published: 2022-04-25T04:30:00.000Z - Updated: 2025-04-16T22:34:49.000Z - Description: Linux is a multi-user operating system, which means that several users can interact the system at the same time. As a system administrator, you are in charge of managing the system's users and groups, which includes adding and deleting users and assigning them to various groups. - Author: Aleksandra Sloan - Tags: how to 🪄, linux 🐧, terminal Just like most things when it comes to Linux there's more than one way that we can do just about everything and adding users is no exception. Especially when it comes to servers, commonly, Linux servers won't have a desktop environment – Another reason to learn the command line. Let us jump! ## **`useradd`** Command Remember, only root or users with `sudo` privileges can use the `useradd` command to create new user accounts. When run, `useradd` command it performs the following major steps: - It edits **/etc/passwd**, **/etc/shadow**, **/etc/group** and **/etc/gshadow** files for the newly created user accounts. - Creates and populates a home directory for the new user. - Sets permissions and ownerships to the home directory. ### Create a New User To create a new user account, run the `useradd` command followed by the name of the user. ```zsh $ sudo useradd darthvader ``` ps: when run without any option, `useradd` creates a new user account using the default settings specified in that `/etc/default/useradd` file. The command also adds an entry to the `/etc/passwd`, `/etc/shadow,/etc/group` and `/etc/gshadow` files. When we add a new user in Linux with the **`useradd`** command it gets created in a locked state and to unlock that user account, we need to set a password for that account with the **`passwd`** command. ```zsh $ sudo passwd darthvader ``` You will be prompted to enter and confirm the password. Make sure you use a strong password. ```zsh OUPUT sudo passwd darthvader New password: Retype new password: passwd: password updated successfully ``` Once a new user is created, its entry is automatically added to the **`/etc/passwd`** file. This file is used to store the user’s information and the entry looks like this. ```zsh $ cat /etc/passwd | grep darthvader OUTPUT Darthvader:x:1004:1004::/home/darthvader:/bin/zsh ``` The above OUTPUT contains a set of seven colon-separated fields, each field has its own meaning. - **Username**: User login name used to login into the system. It should be between 1 to 32 characters long. - **Password**: User's hash password (or x character) stored in **`/etc/shadow`** file in an encrypted format. - **User ID (UID)**: Every user must have a User **ID** (**UID**) User Identification Number. By default, **UID 0** is reserved for the root user and UIDs ranging from **1-99** are reserved for other predefined accounts. Further UIDs ranging from **100-999** are reserved for system accounts and groups. - **Group ID (GID)**: The primary Group ID (**GID**) Group Identification Number stored in the **`/etc/group`** file. - **User Info**: This field is optional and allows you to define extra information about the user. For example, the user's full name. This field is filled by the `finger` command. - **Home Directory**: The absolute location of the user’s home directory. - **Shell**: The absolute location of a user’s shell i.e. **/bin/zsh** ### Add a New User and Create a Home Directory On most Linux distributions, when creating a new user account with `useradd`, the user’s home directory is not created. Use the `-m` (`--create-home`) option to create the user home directory as `/home/username`: ```zsh $ sudo useradd -m darthvader $ sudo passwd darthvader ``` The command above creates the new user’s home directory and copies files from `/etc/skel` directory to the user’s home directory. ```zsh $ ls -la /home/darthvader total 84 drwxr-xr-x 4 darthvader darthvader 4096 Oct 2 13:15 . drwxr-xr-x 6 root root 4096 Sep 30 18:24 .. -rw-r--r-- 1 darthvader darthvader 220 Feb 25 2020 .bash_logout -rw-r--r-- 1 darthvader darthvader 3771 Feb 25 2020 .bashrc drwxr-xr-x 4 darthvader darthvader 4096 Oct 2 12:58 .cache drwxr-xr-x 3 darthvader darthvader 4096 Oct 2 12:58 .local -rw-r--r-- 1 darthvader darthvader 807 Feb 25 2020 .profile -rw-rw-r-- 1 darthvader darthvader 49032 Oct 2 12:59 .zcompdump -rw------- 1 darthvader darthvader 99 Oct 2 13:15 .zsh_history -rw-r--r-- 1 darthvader darthvader 1295 Oct 2 12:59 .zshrc ``` ### Create a User with a Different Home Directory According with `man useradd`, `-d /var/www/mercury mercury` option will **not create** the directory `/var/www/mercury`, if this is **missing**. Thus, we first have to create it manually. To do this, run the following commands in Terminal: ```zsh $ sudo -i #to get root privileges $ mkdir /var/www/mercury $ cp -rT /etc/skel /var/www/mercury ``` Only then, we can run: ```zsh $ sudo useradd -d /var/www/mercury mercury $ sudo chown -R mercury:mercury /var/www/mercury $ sudo passwd mercury ``` or we can run the combining `-m` and `-d` options as below. ```zsh $ sudo useradd -m -d /var/www/mercury ``` PS: the order here is very important `-m` & `-d` and not the other way around. We can see the user's home directory and other user-related information like user ID, group ID, shell, and comments. ```zsh $ cat /etc/passwd | grep mercury OUTPUT mercury:x:1005:1005::/var/www/mercury:/bin/zsh ``` ### Add a New User with a Specific User ID In Linux and Unix-like operating systems, users are identified by a unique UID and username. User identifier (UID) is a unique positive integer assigned by the Linux system to each user. The UID and other access control policies are used to determine the types of actions a user can perform on system resources. By default, when a new user is created, the system assigns the next available UID from the range of user IDs specified in the `login.defs` file. Run `useradd` with the `-u` (`--uid`) option to create a user with a specific UID such as: ``` $ sudo useradd -u 1808 neptune $ sudo passwd neptune or $ sudo useradd -mu 1808 neptune $ sudo passwd neptune ``` You can verify the user’s UID, using the `id` command: ``` $ id -u mercury OUTPUT 1808 ``` ### Add a User with a Specific Login Shell By default, the new user's login shell is set to the one provided in the /etc/default/useradd file. In some distributions, the default shell may be set to either `/bin/sh` or `/bin/bash`. But sometimes, we need to add users who have nothing to do with the login shell. /sbin/nologin or/usr/sbin/nologin is used as a shell in Linux to politely refuse a login attempt. It is a per-account way to disable login on Linux. Setting the shell to /usr/sbin/nologin makes it impossible for that user to SSH into a server. It is typically used by many system services that need an account but do not want to create security issues by granting them login access. Here in this example, will add a user '**io**' without a login shell. Use the `-s` (`--shell`) option to specify the new user’s login shell: ``` $ sudo useradd -s /usr/sbin/nologin io ``` Let's check the user entry in the `/etc/passwd` file to verify the user’s login shell. ``` $ sudo grep io /etc/passwd OUTPUT io:x:1011:1011::/home/io:/usr/sbin/nologin ``` ### Add a User with Custom Comments The **`-c`** ( --comment) option allows you to add a short description for a given user, such as the user’s **full name**, **phone number,** ... to **/etc/passwd** file. Now, let's create a new user named `europa` with text string `Test User Account` as a comment. ``` $ sudo useradd -c "Test User Account" europa ``` Let's check. ``` $ sudo grep europa /etc/passwd OUTPUT europa:x:1112:1112:Test User Account:/home/europa:/bin/zsh ``` Also, the comment field/ record is known as; `GECOS` on UNIX; just that you don't die stupid! 🤩😅 ### Add a User with Specific: Home Directory, Shell, user ID# along with a Comment The following command is a combination of the above-seen commands. ``` $ sudo useradd -m -d /var/www/jupiter -s /bin/bash -c "#1234567" -u 1111 callisto ``` Let's check our user entry in the `/etc/passwd` file to verify all that. ``` $ sudo grep callisto /etc/passwd OUTPUT callisto:x:1111:1111:#1234567:/var/www/jupiter:/bin/bash ``` ### Create a User with an Expiry Date This comes in handy when creating temporary accounts. Use the -e (—expiredate) option to set an expiration date for new user accounts. The date format must be as `YYYY-MM-DD`. Let's create a new user account named `voyager1` with an expiry time set to January 01, 2025. ``` $ sudo useradd -e 2025-01-01 voyager1 ``` Run the `chage` command to verify the user account expiry date. ``` $ sudo chage -l voyager1 OUTPUT Last password change : Oct 05, 2021 Password expires : never Password inactive : never Account expires : Jan 01, 2025 Minimum number of days between password change : 0 Maximum number of days between password change : 99999 Number of days of warning before password expires : 7 ``` ## `userdel` Command Remember, only root or users with `sudo` privileges can use the `userdel` command to create new user accounts. ### Delete a User Let's delete a user account named `io` using the `userdel` command. ``` $ sudo userdel io ``` The command removes the user entries from the `/etc/passwd` as well as `/etc/shadow,` files. In most Linux distributions, when removing a user account using `userdel`, the user's home and mail spool directories are not removed. Now, let's run the `-r` (`--remove`) option to force `userdel` to remove the user’s home directory and mail spool: ``` $ sudo userdel -r io ``` Also, the `userdel` command does not allow to remove any user if he/she is still logged in. It is recommended to log out the user and kill all user’s running processes using the `killall` command: ``` $ sudo killall -u io ``` Once done, you can remove the user. Another alternative is to use the `-f` (`--force`) option that tells `userdel` to forcefully remove the user account, whether or not the user is still logged in or if there are running processes attached to the user. ``` $ sudo userdel -f io ``` Well, we have shown you how to create/delete new user accounts using the `useradd` / `userdel` command. Hope we've made your day better and... ... remember; keep on learning!