Linux is a multi-user Working System (OS). Which means that a number of customers can use the identical Linux system on the identical time. As a system administrator or sys admin, you want to have the ability to management who has entry to the system always. Observe by way of this information to see how one can handle customers in your Linux machine.
Creating Customers in Linux from the Terminal
So as to add a brand new consumer to Linux through the terminal, use the useradd command. The syntax is beneath:
useradd [options] username
The useradd command requires administrative privileges with a view to run it. Due to this fact, you will need to prefix it with sudo.
Normally, you will want to your consumer to have a house listing. Including the -m choice will allow sys admins to realize this. The consumer’s residence listing might be positioned at /residence/username. Right here is how that appears in code:
$ sudo useradd -m userY # residence listing at /residence/userY
The consumer we created above can’t entry the system as of but since they don’t have a password. You will want to make use of the passwd device to handle your customers’ passwords.
To create a password for userY, run the command beneath:
$ passwd userY
You may be requested to create and make sure the brand new consumer’s password. The output in your terminal ought to look much like the one beneath:
New password: Retype new password: passwd: password up to date efficiently
The identical passwd command can be utilized to alter a consumer’s present password. Merely run the identical command (because the earlier one) with sudo privileges to take action, as proven beneath:
$ sudo passwd userY # altering a consumer's password
To login in your terminal as the brand new consumer, merely sort the su command, adopted by the username:
su userY Password: $
When that you must exit from this consumer’s shell, you need to use the exit command.
Instance of Linux Terminal Window (courtesy Linux.com)
See Who Is Accessing a Linux System By the Terminal
You could wish to know which consumer is at the moment utilizing the system. On this case, use the who or w instructions. The distinction between the 2 instructions is that w provides you extra detailed data than who. To make use of the who command, merely enter:
$ who
To know what number of customers are in your Linux system, you must open the /and so on/passwd file. Every line on this file represents the data of a consumer separated by colons. All customers are allowed to learn from this file.
Ideally, it’s best to be capable to add a consumer by including an entry to the /and so on/passwd file. This will not be attainable, although, as detailed beneath.
By default, Linux programs encrypt a consumer’s password subject and retailer its worth within the /and so on/shadow file. Solely the foundation consumer has entry to this file. Because of this, you’ll see the worth x the place a consumer’s password is meant to be within the /and so on/passwd file.
Due to this fact, you’ll be able to solely use the passwd device to create a consumer in case your system implements encryption.
Usually, it’s not advisable to straight modify the /and so on/passwd file. Doing so could create safety vulnerabilities. For instance, deleting a consumer entry from the file doesn’t imply that the consumer’s entry has been revoked. A malicious actor can subsequently exploit this vulnerability and achieve entry to the system.
Managing Consumer Entry within the Linux Terminal
Linux lets you modify, revoke or restrict consumer entry. You should use the usermod command to change all of the details about a consumer. It takes in the identical choices because the useradd command.
For instance, to alter a consumer’s identify you enter:
$ sudo usermod userY userZ
As a system administrator, you could wish to revoke entry to a sure account. To lock an account, use the passwd device with the -l choice. Use the -u choice to unlock it, as proven beneath:
$ passwd -l userZ $ passwd -u userZ
Managing Passwords in Linux Terminal
You could must outline an expiry date for a consumer’s password. The chage command permits you to do that. The -e choice permits system admins to specify an expiry date for a consumer’s password within the mm/dd/yyyy format. On expiry, the consumer might be prompted to enter a brand new password. Right here is the syntax:
$ chage -e 08/25/2025 userZ
You may as well specify the utmost variety of days a consumer’s password ought to be energetic utilizing the -M choice.
$ chage -M 6 userZ # this consumer's password will expire in 6 days
Eradicating Customers within the Linux Terminal
To take away a consumer account, use the userdel command. For those who embody the -r choice, the consumer’s residence listing may also be deleted.
$ userdel -r userY
Managing Linux Customers within the Terminal
This information has proven you the way you need to use the command line to handle Linux customers. Recall that it’s advisable so that you can use the passwd device to create new customers, regardless that your Linux system could not implement password encryption. This fashion, you shield your system from unintended vulnerabilities.
