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useradd command

By Sai Rohith Karanam


Use of this command:

'useradd' command is used to add a new user into the system. In other words, it creates a new login account for a different user. 

Remember that only the root user can add new users into the system.


You can check who are the existing users in /etc/passwd file


To simply add a user to the system, this command is used:

useradd virat

This command adds the user named virat into the system and you can check whether virat is added or not in the /etc/passwd file.

Here, You can see that I have shifted to root user to add the user 'virat'

You can see that user virat has been added to /etc/passwd file
This is just a basic way of adding users into the system.

Now let us explore the various options of useradd command.

But before going to that, let us understand all the fields in /etc/passwd file.

There are 7 fields in /etc/passwd file for every user.

1. Username: Name of the user.

2. Password: This password is not visible. (marked x)

3. UID: User ID

4. GID: The group ID of which the user belongs to.

5. Comment field: Here the user can write anything which he/she wants to. This is optional.

6. User home directory: The user's home directory is shown in this field. By default, the user's home directory will be /home/username.

7. Default shell: This shows the name of the default shell with which user interacts. By default, it is bash shell.

Now that you've known about the fields of /etc/passwd file, let us explore various options of useradd command.

1. useradd -c: To add a comment

In /etc/passwd file, You can see that comment field is not empty

2. useradd -d: To set a home directory. If you don't set, the default one will be /home/username

Originally, the home directory should be /home/Mahender. but with -c option, we changed to /home/Mahi

3. useradd -u: Customize UID, set UID of your choice.

Here, we have set UID of Anand as per our choice (100787)

4. useradd -g: Add the user to an existing group with that existing group's GID.

Here we have added Praneeth to an existing group. The existing group's id is 1001.

5. useradd -G: Add the user to supplementary groups, i.e, other than the default primary group.

Here, -g for primary group, -G option for supplementary groups. You can view all the groups of a user with 'lid username'


6. useradd -e: Add the user with an expiration date. After the specified date, the user is disabled.

You can see the expiration date and other info the user with chage -l username

7. useradd -s: sets the default shell for the user. If this is not set, the default shell will be bash.

By default it should be /bin/bash. But with -s option, we changed to korne shell. (/bin/ksh)



Fun part:

Which command is used to create a user by taking password on the spot?

Post your answer in the comment section if you got it.










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