User management on Linux can be done in three complementary ways. You can use the graphical tools provided by your distribution. These tools have a look and feel that depends on the distribution. If you are a novice Linux user on your home system, then use the graphical tool that is provided by your distribution. This will make sure that you do not run into problems.

Another option is to use command line tools like useradd, usermod, gpasswd, passwd and others. Server administrators are likely to use these tools, since they are familiar and very similar across many different distributions. This guide will focus on these command line tools.

A third and rather extremist way is to edit the local configuration files directly using vi (or vipw/vigr). Do not attempt this as a novice on production systems!

/etc/passwd

The local user database on Linux (and on most Unixes) is /etc/passwd.

As you can see, this file contains seven columns separated by a colon. The columns contain the username, an x, the user id, the primary group id, a description, the name of the home directory, and the login shell. More information can be found by typing the following command

#man 5 passwd

Useradd

You can add users with the useradd command. The example below shows how to add a user named chris (last parameter) and at the same time forcing the creation of the home directory (-m), setting the name of the home directory (-d), and setting a description (-c).

/etc/default/useradd

Both Red Hat Enterprise Linux and Debian/Ubuntu have a file called /etc/default/useradd that contains some default user options. Besides using cat to display this file, you can also use the following command

#useradd -D

userdel

You can delete the user chris with userdel. The -r option of userdel will also remove the home directory.

#userdel -r chris

usermod

You can modify the properties of a user with the usermod command. This example uses usermod to change the description of the user chris

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Ruwantha Nissanka

Ruwantha Nissanka is a Professional Cyber Security Engineer from Sri lanka with having a demonstrated history of providing cyber security services for multiple organizations in Sri Lanka. He is a positive person who wants to believe the best in others and he likes to help, encourage people and make them feel good.