Creating New Users

For security reasons, working as the root user on a Linux system is not recommended, since even small mistakes in commands can cause irreversible damage to files and the system.

The best approach is to create an additional VPS user with sudo privileges. The sudo mechanism lets this user perform operations with administrator (root) privileges when needed.

You can also use these instructions to create regular system users (without sudo privileges) — just complete the first three steps.

Creating a user with sudo privileges

1. Create a new user (username in this example) with the following command:

adduser username

By default, the new user is added to a group with the same name, and a home directory is created for them.

2. On Ubuntu / Debian, you will be asked to enter the user's password. You need to enter it twice. Keep in mind that password characters are not displayed in the Linux console as you type.

On CentOS, run this command to set the password:

passwd username

Then enter the password and confirm it.

3. On Ubuntu / Debian, you will also be asked for additional information about the user (such as full name, phone number, and so on). You can enter this information or leave the fields empty by pressing Enter to use the default values. Then press Y to confirm.

On CentOS, if you need to add this information, run this command:

chfn username

At this point, a regular user (without sudo privileges) has been created.

4. To grant the user sudo privileges, add them to the sudo group. You can do this with the following commands.

On Ubuntu / Debian:

usermod -aG sudo username

On CentOS:

usermod -aG wheel username

5. Test the new user. To do this, switch to their account:

su - username

The system will ask for the user's password (the first time you use sudo). After that, you can try running any command with sudo privileges. For example, you can list the contents of the /root directory, which regular users cannot access:

sudo ls -la /root

If the directory contents are displayed, the new user is working correctly.

If root uses SSH key authentication

If you logged in as root with an SSH key, password authentication for SSH is disabled. To log in successfully, you need to add a copy of your local public key to the new user's ~/.ssh/authorized_keys file. Since your public key is already in the root account's ~/.ssh/authorized_keys file, you can copy this file to the new user's home directory with the cp command and set the permissions with chown.

Copy the entire directory to the new user's home directory:

cp -r ~/.ssh /home/username

Make the username user the owner of this directory (a group with the same name is also created):

chown -R username:username /home/username/.ssh

Now you can log in to the server as the new user without a password:

ssh username@your_server_ip

If you need to run a command with administrator privileges, type sudo before the command, for example:

sudo

 command

The first time you use sudo (and periodically after that), you will be asked for the regular user's password.

6. This step is optional, but for better security you can disable remote access for the root superuser. Users will then always have to log in with their own accounts, which lets you track activity on the server, see who made changes, and so on. To disable root access, open the /etc/ssh/sshd_config file:

sudo nano /etc/ssh/sshd_config

Find the PermitRootLogin line and replace its current value with:

PermitRootLogin no

Save the changes and close the editor (key combination Ctrl X -> Y -> Enter).

Then restart the SSH service with the following commands:

On Ubuntu / Debian:

sudo service ssh restart

On CentOS:

sudo service sshd restart

Other user management commands

If you need to add a user to another group, create that group first:

groupadd group_name

On Ubuntu and Debian, you can also use the addgroup command to create a group:

addgroup group_name

Then add the user to the group with the usermod command:

usermod -G group_name username

To change the user's primary group, use the -g option:

usermod -g group_name username

To change the user's home directory, use the command:

usermod -d path/to/new_directory username

To get information about a user, use the command:

id username

The output will look something like this:

uid=1000(username) gid=1000(username) groups=1000(username),27(sudo)

You can change the user's password with the command:

passwd username

To view a list of all users, use the command:

cat /etc/passwd

To get just the list of user names, without additional information, use:

sed 's/:.*//' /etc/passwd

To see which users are currently logged in, use the w command.

You can delete a user with the command:

deluser username

To delete a group, use:

delgroup group_name