user management Archives • Page 3 of 3 • Linux Tips

How To: Add A User To A Group

Today’s article is going to teach you how to add a user to a group. It’s not particularly difficult, but it’s something everyone should know. If you don’t know how to add a user to a group, this article is meant for you.

This article is going to make a few assumptions. The first is that you’re familiar with cat /etc/passwd which will tell you what groups a user belongs to. It also assumes that you’re familiar with cat /etc/group – where you can find supplementary information.

Furthermore, you should also be aware of the groups command, which is a handy command, probably worthy of its own article, that lets you know what groups you already belong to. So, there’s a bit you’re expected to know already, or at least be familiar with conceptually, but trust me when I say this is a very simple article and very straightforward.

Anyhow, if you’ve looked at those previous commands, you’ll see there are a lot of groups. Your user may or may not be a member of those groups, as the groups command will let you know. For myriad reasons, you may wish to add yourself or another user to different groups. Well, that’s what this article is actually about. It’s about showing you how to …

Add A User To A Group:

This article requires an open terminal, like many other articles on this site. If you don’t know how to open the terminal, you can do so with your keyboard – just press CTRL + ALT + T and your default terminal should open.

The command we’ll be using for this exercise is ‘usermod‘. You can get a head start by using ‘man usermod‘ but we really won’t be needing most of that information. In reality, we only care about a couple of the flags. Still, usermod is a pretty expansive command, with many options. Still, it defines itself simply as:

usermod – modify a user account

See? Pretty straightforward still. The command we actually want is:

sudo usermod -a -G <group_name> <user_name>

1	sudo usermod -a -G <group_name> <user_name>

The -a means append (add) the user. The -G means groups – so the -a -G means add a user to a group. You can verify the command worked (though, well, you really don’t need to – ’cause, assuming you did it properly it’ll work) with the following:

grep <user_name> /etc/group

1	grep <user_name> /etc/group

See? That’s it. You’ve learned how to add a user to a group – in under 500 words!

Closure:

Yup, it’s a nice and easy article for a skill you may need as you work with advanced group permissions. If you want to refine the permissions in your system, the sky’s the limit and it’s easy enough to add a user to a group if you need to. So, there’s another tool in your toolbox.

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Create A New User With SUDO Privileges In Ubuntu

It’s not unusual to want to create a new user with sudo privileges and it’s actually really easy. This will be just a quick article that explains how. It’s not exactly a complex operation.

This article doesn’t cover other distros! It has only been tested in a couple of Ubuntu derivatives and not all distros come with ‘adduser’. It should probably work if you install ‘adduser’ where available, but that’s entirely untested by me. Give it a shot and let me know in a comment if it works out for you.

You may want a multi-user environment, you may want different logs for different users, you may want some customization with one user, you might want to test things with a separate user, etc… There are tons of reasons for wanting a different account and wanting a new user with sudo privileges.

I shouldn’t need to mention this, but sudo stands for ‘superuser do’. Users that belong to the sudo group are pretty much omnipotent. They can access anything, change anything, and do anything they please. You’ll use sudo to do things like install software or edit system files.

Anyhow, I’ll explain how to create a new user with sudo privileges in this article. It’s a pretty easy task and you shouldn’t have much trouble with this one.

Create New User With SUDO Privileges:

The tool we’ll be starting with is called ‘adduser‘, and the name tells you what it does. With your terminal now open, you start by entering the following to add a new user:

sudo adduser <new_user_name>

1	sudo adduser <new_user_name>

Once you’ve done that, you’ll be asked to type the new user’s password twice, and then you can fill in some additional information for that user. Those steps aren’t necessary, but you will want to add a password for the user – and definitely so because it’s an account that has access to sudo.

Now that you have created a new user, you’ll need to modify that user. The newly created user doesn’t come with sudo access by default, you need to grant it. The tool we’ll be using for this is ‘usermod‘ and the command to make the new account a new user with sudo privileges is:

sudo usermod -aG sudo <new_user_name>

1	sudo usermod -aG sudo <new_user_name>

At this point, you should be able to login and use the newly minted user account. Indeed, you should have a new user account and that new account should have sudo privileges.

CLOSURE:

See? I told you that this wouldn’t be a long or difficult article. If you want a new account and you want that account to have sudo privileges, it’s just a couple of easy commands away. This is yet another article in what’s turning out to be quite a long list of articles.

How To: List All Users In Linux

If you want to list all users in Linux, this is the article for you. It should be a fairly short article, but it should tell you how to list all users. So, there’s that. By that, I mean it’ll probably do what it says on the tin, namely telling you how to list all your users.

You may want to check the list of users from time to time. Applications may add users, you may have added users, malicious software or people may have added users, etc… There are other reasons to list all users, but you get the idea.

This is a beginner-level exercise, so you shouldn’t have any difficulty with it. It should also be reasonably short, which is nice! If you find any mistakes or have any questions, scroll down and leave a comment. You can also ask on the lovely Linux.org forums.

Without further ado…

List All Users:

Once again, we start with opening the terminal. To do this, you just press CTRL + ALT + T and the terminal should open. That’s true on most distros that I’ve encountered. If not, you will still need an open terminal.

Got it open? Good, ’cause it’s a pretty easy operation. The file you’re looking for is ‘/etc/passwd’, which is a plain text file that’s in conjunction with the /etc/shadow file. Like most text files, it’s easy enough to work with them in the terminal.

You probably shouldn’t edit /etc/passwd by hand, but we’re just going to be viewing it.

So, to show the content of the file (and see the list of users):

cat /etc/passwd

1	cat /etc/passwd

If you want to show fewer results at a time, you can just use:

less /etc/passwd

1	less /etc/passwd

If you want, you can ‘grep’ a specific user. Just pipe the output to grep and you’re good to go. It looks like this:

cat /etc/passwd | grep root

1	cat /etc/passwd \| grep root

If you want to use that format AND have numbered lines, one way of finding out how many users there are, then just use:

less -N /etc/passwd

1	less -N /etc/passwd

Though you could just as easily have used this to get the number:

cat /etc/passwd | wc -l

1	cat /etc/passwd \| wc -l

If you want to list just the users, you can use ‘awk’ and pick the first column like this:

awk -F: '{ print $1}' /etc/passwd

1	awk -F: '{ print $1}' /etc/passwd

And that’s about it, really. You’ve now listed all the users – and counted ’em!

Closure:

That’s it! That’s all there is to it, and you’ve learned a little bit more – this time how to list users in Linux. I told you that it’d be pretty painless and easy. Plus, this is another article for the books – and this one authored early enough to give me some time to keep scheduling them ahead of time.

How To: Properly Delete a User’s Account

Today’s article will show you how to properly delete a user’s account. It’s a pretty basic task and an astute observer would note that I’ve not yet written an article about creating user accounts. I may have to write said article at some point, because why not? This promises to be a pretty easy and brief article!

When you install some software, it may add a user. When you remove that software, it may just leave that user behind. You may have multiple people using your devices, or you may be working in a corporate environment. Either way, there comes a time when you may want to clean house and delete user accounts that are no longer necessary.

It can be just a little tricky to properly delete a user’s account, so I figure it’s something worth covering. The tool we’ll be using is ‘userdel‘ and my checking indicates it’s universal. Let’s get to it!

Delete A User:

I’m gonna assume that you already know the name of the user you’d like to remove from your system. With that information in hand, let’s open the terminal by pressing CTRL + ALT + T on your keyboard.

Once you have the terminal open, you can do a basic user delete with:

sudo userdel <user>

1	sudo userdel <user>

If the user has a /home/user directory, you can delete that at the same time with this:

sudo userdel -r <user>

1	sudo userdel -r <user>

Seems nice and easy, right? Well, before you should run any of those commands you should be sure that the user is both not logged in and has no processes running in their name. If you do have either of those things, you will want to run this command before running either of the userdel commands above:

sudo killall -u <user>

1	sudo killall -u <user>

You can also try the -f (force) option with the userdel, but I’ve never had good luck with that. So, your better using killall before you use userdel. If you’d like to try it, here it is:

sudo userdel -f <user>

1	sudo userdel -f <user>

And that’s actually everything. There’s likely to also be a graphical way to delete users and that’ll depend on your desktop environment. Rather than play around with learning and documenting all those, you can just do it in the terminal where it’s easy enough and equally effective.

Closure:

And now you know how to delete a user account, and how to do it properly. Indeed, this is another article in the books and hopefully this one will help people for years to come. It’s a good idea to not have pointless users around on your system. If they exist, they can be used.