Introduction

One of the most basic tasks to that you should know how to do on a fresh Linux server is add and remove users. When you create a new server, you are only given the root account by default.
While this gives you a lot of power and flexibility, it is also dangerous and can be destructive. It is almost always a better idea to add an additional, unprivileged user to do common tasks. You also should create additional accounts for any other users you may have on your system. Each user should have a different account.
You can still acquire administrator privileges when you need them through a mechanism called sudo. In this guide we will cover how to create user accounts, assign sudo privileges, and delete users.

How To Add a User

If you are signed in as the root user, you can create a new user at any time by typing:

adduser newuser

If you are signed in as a non-root user who has been given sudo privileges, as demonstrated in the initial server setup guide, you can add a new user by typing:

sudo adduser newuser

Either way, you will be asked a series of questions. The procedure will be:

Assign and confirm a password for the new user
Enter any additional information about the new user. This is entirely optional and can be skipped by hitting “ENTER” if you don’t wish to utilize these fields.
Finally, you’ll be asked to confirm that the information you provided was correct. Type “Y” to continue.

Your new user is now ready for use! You can now log in using the password you set up.
Note: Continue on if you need your new user to have access to administrative functionality.

How To Grant a User Sudo Privileges

If your new user should have the ability to execute commands with root (administrative) privileges, you will need to give the new user access to sudo.
We can do this by using the visudo command, which opens the appropriate configuration file in your editor. This is the safest way to make these changes.
If you are currently signed in as the root user, type:

visudo

If you are signed in using a non-root user with sudo privileges, type:

sudo visudo

Search for the line that looks like this:

root    ALL=(ALL:ALL) ALL

Below this line, copy the format you see here, changing only the word “root” to reference the new user that you would like to give sudo privileges to:

root    ALL=(ALL:ALL) ALL
newuser ALL=(ALL:ALL) ALL

You should add a new line like this for each user that should be given full sudo privileges. When you are finished, you can save and close the file by hitting CTRL-X, followed by “Y”, and then hit “ENTER” to confirm.
Now, your new user is able to execute commands with administrative privileges.
When signed in as the new user, you can execute commands as your regular user by typing commands as normal:

some_command

You can execute the same command with administrative privileges by typing sudo ahead of the command:

sudo some_command

You will be prompted to enter the password of the regular user account you are signed in as.

How To Delete a User

In the event that you no longer need a user, it is best to delete the old account.
You can delete the user itself, without deleting any of his or her files by typing this as root:

deluser newuser

If you are signed in as another non-root user with sudo privileges, you could instead type:

sudo deluser newuser

If, instead, you want to delete the user’s home directory when the user is deleted, you can issue the following command as root:

deluser --remove-home newuser

If you’re running this as a non-root user with sudo privileges, you would instead type:

sudo deluser --remove-home newuser

If you had previously configured sudo privileges for the user you deleted, you may want to remove the relevant line again by typing:

visudo

Or use this if you are a non-root user with sudo privileges:

sudo visudo


root    ALL=(ALL:ALL) ALL
newuser ALL=(ALL:ALL) ALL   # DELETE THIS LINE

This will prevent a new user created with the same name from being accidentally given sudo privileges.

Conclusion

You should now have a fairly good handle on how to add and remove users from your Ubuntu 14.04 system. Effective user management will allow you to separate users and give them only the access that they are required to do their job.
For more information about how to configure sudo, check out our guide on how to edit the sudoers file here.