How to Manage Linux Users and Groups

Adding Users

# Ubuntu/Debian
sudo adduser alice

# CentOS/AlmaLinux
sudo useradd alice
sudo passwd alice

Tip: On Debian-based systems adduser is more user-friendly than useradd.

Deleting Users

# remove user (but keep home dir)
sudo deluser alice   # Debian/Ubuntu
sudo userdel alice   # CentOS/AlmaLinux

# remove user + home directory
sudo deluser --remove-home alice
sudo userdel -r alice

Managing Groups

# create new group
sudo groupadd developers

# add user to group
sudo usermod -aG developers alice

# show user’s groups
groups alice

# remove group
sudo groupdel developers

Granting Sudo Access

Add user to sudo group (Ubuntu/Debian) or wheel group (CentOS/AlmaLinux):

# Debian/Ubuntu
sudo usermod -aG sudo alice

# CentOS/AlmaLinux
sudo usermod -aG wheel alice

Edit sudoers file safely:

sudo visudo

Managing Passwords

# change password for user
sudo passwd alice

# force user to reset password on next login
sudo passwd -e alice

Viewing User Information

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

# detailed user info
id alice

# last login info
lastlog | grep alice