Linux Server Administration

This article covers the essential tasks for administering a Linux server: managing users, controlling services, and monitoring system resources.

User Management

# Create a new user
sudo adduser username

# Add user to a group (e.g. sudo)
sudo usermod -aG sudo username

# Switch to another user
su - username

# Delete a user
sudo deluser username

Managing Services with systemd

Most modern Linux distributions use systemd to manage background services.

# Check the status of a service
sudo systemctl status nginx

# Start / stop a service
sudo systemctl start nginx
sudo systemctl stop nginx

# Restart a service
sudo systemctl restart nginx

# Enable a service to start on boot
sudo systemctl enable nginx

# Disable autostart
sudo systemctl disable nginx

Viewing Logs

# View system logs
sudo journalctl

# Follow logs for a specific service
sudo journalctl -u nginx -f

# Show logs from the last hour
sudo journalctl --since "1 hour ago"

Monitoring Resources

# Show CPU and memory usage (interactive)
top
htop  # more user-friendly, may need to be installed

# Disk usage
df -h

# Directory size
du -sh /var/log

# Running processes
ps aux

# Network connections
ss -tulnp

Firewall (UFW)

UFW (Uncomplicated Firewall) is the standard firewall tool on Ubuntu/Debian systems.

# Check firewall status
sudo ufw status

# Allow a port
sudo ufw allow 80
sudo ufw allow 443
sudo ufw allow ssh

# Enable the firewall
sudo ufw enable

Package Management

# Update package list and upgrade installed packages
sudo apt update && sudo apt upgrade

# Install a package
sudo apt install <package>

# Remove a package
sudo apt remove <package>