How to Manage Users on Linux

Why Manage Users on Linux Matters

Linux is a multi-user system. Even if you’re the only one using your machine, proper user management ensures security, permissions control, and system stability. Each user gets their own home directory, shell, and permissions.

Adding a New User

On Ubuntu/Debian:

sudo adduser alex

This creates the user alex, assigns a home directory (/home/alex), and prompts you to set a password.

On CentOS/AlmaLinux:

sudo adduser alex
sudo passwd alex

The second command sets the user’s password.

Granting Sudo (Admin) Privileges

To allow a user to run administrative commands:

sudo usermod -aG sudo alex    # Ubuntu/Debian
sudo usermod -aG wheel alex   # CentOS/AlmaLinux

The -aG flag appends the user to a group (sudo or wheel depending on distro).

Switching Between Users

# switch to another user
su - alex

# return to your account
exit

You can also log in as a user via SSH:

ssh alex@server-ip

Changing User Settings

Modify user properties with usermod:

# change username
sudo usermod -l newname oldname

# change home directory
sudo usermod -d /home/newdir -m alex

# change default shell
sudo usermod -s /bin/bash alex

Deleting Users

To remove a user:

sudo deluser alex        # Ubuntu/Debian
sudo userdel alex        # CentOS/AlmaLinux

To delete the user and their home directory:

sudo deluser --remove-home alex   # Ubuntu/Debian
sudo userdel -r alex              # CentOS/AlmaLinux

Viewing Users & Groups

# list all users
cut -d: -f1 /etc/passwd

# list all groups
cut -d: -f1 /etc/group

# show groups for a specific user
groups alex