How to add users in Linux “useradd”

In Linux, a ‘useradd‘ command is a low-level utility that is used for adding/creating user accounts in Linux and other Unix-like operating systems. The ‘adduser‘ is much similar to useradd command, because it is just a symbolic link to it.

Basic syntax of command is:

useradd [options] username

1. How to Add a New User in Linux

For example, to add a new user called ‘tecmint‘, use the following command.

[[email protected] ~]# useradd zetuser

When we add a new user in Linux with ‘useradd‘ command it gets created in locked state and to unlock that user account, we need to set a password for that account with ‘passwd‘ command.

[[email protected]~]# passwd zetuser
Changing password for user zetuser.
New UNIX password:
Retype new UNIX password:
passwd: all authentication tokens updated successfully.

Once a new user created, it’s entry automatically added to the ‘/etc/passwd‘ file. The file is used to store users information and the entry should be.

zetuser:x:502:502::/home/zetuser:/bin/bash

The above entry contains a set of seven colon-separated fields, each field has it’s own meaning. Let’s see what are these fields:

2. Create a User with Different Home Directory

[[email protected]~]# useradd -d /project/step1 newuser

You can see the user home directory and other user related information like user id, group id, shell and comments.

[[email protected] ~]# cat /etc/passwd | grep newuser
newuser:x:505:505::/project/step1:/bin/bash

3. Create a User with Specific User ID

In Linux, every user has its own UID (Unique Identification Number). By default, whenever we create a new user accounts in Linux, it assigns userid 500, 501, 502 and so on…

But, we can create user’s with custom userid with ‘-u‘ option. For example, the following command will create a user ‘navin‘ with custom userid ‘999‘.

[[email protected] ~]# useradd -u 999 david

Now, let’s verify that the user created with a defined userid (999) using following command.

[[email protected] ~]# cat /etc/passwd | grep david
david:x:999:999::/home/david:/bin/bash

4. Add a User without Home Directory

To create user’s without their home directories, ‘-M‘ is used. For example, the following command will create a user ‘marcel‘ without a home directory.

[[email protected] ~]# useradd -M marcel

Now, let’s verify that the user is created without home directory, using ls command.

[[email protected] ~]# ls -l /home/marcel
ls: cannot access /home/marcel: No such file or directory

5. Create a User with Account Expiry Date

By default, when we add user’s with ‘useradd‘ command user account never get expires i.e their expiry date is set to 0 (means never expired).

However, we can set the expiry date using ‘-e‘ option, that sets date in YYYY-MM-DD format. This is helpful for creating temporary accounts for a specific period of time.

Here in this example, we create a user ‘laur‘ with account expiry date i.e. 30th October 2014 in YYYY-MM-DDformat.

[[email protected] ~]# useradd -e 2016-10-30 laur

Next, verify the age of account and password with ‘chage‘ command for user ‘laur‘ after setting account expiry date.

[[email protected] ~]# chage -l laur
Last password change : Oct 21, 2016
Password expires : never
Password inactive : never
Account expires : Oct 30, 2016
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

6. Create a User with Password Expiry Date

The ‘-f‘ argument is used to define the number of days after a password expires. A value of 0 inactive the user account as soon as the password has expired. By default, the password expiry value set to -1 means never expire.

Here in this example, we will set a account password expiry date i.e. 20 days on a user ‘laurentiu’ using ‘-e‘ and ‘-f‘ options.

[[email protected] ~]# useradd -e 2016-10-30 -f 20 laurentiu

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