How to Manage Services with systemctl on Linux

What Is systemctl?

On modern Linux systems (Ubuntu 16+, Debian 8+, RHEL/CentOS 7+), systemd manages services. The systemctl command is how you interact with it. Whether you're managing a web server, a database, or a custom application, the commands are always the same.

Core Service Commands

sudo systemctl start nginx          # start a service
sudo systemctl stop nginx           # stop a service
sudo systemctl restart nginx        # stop then start
sudo systemctl reload nginx         # reload config without full restart
sudo systemctl status nginx         # show current status and recent logs

Enable and Disable at Boot

Starting a service with systemctl start only runs it until the next reboot. To make it permanent:

sudo systemctl enable nginx         # start automatically on boot
sudo systemctl disable nginx        # stop starting automatically
sudo systemctl enable --now nginx   # enable AND start immediately

Reading the Status Output

sudo systemctl status ssh

The output tells you:

• Active: active (running) — service is up
• Active: failed — service crashed or failed to start
• Loaded: enabled — will start on boot
• The last few log lines from the service journal

Checking All Services

systemctl list-units --type=service             # all active services
systemctl list-units --type=service --state=failed   # failed services only
systemctl list-unit-files --type=service        # all installed services + enabled state

Common Services to Know

• ssh or sshd — SSH server
• nginx — Nginx web server
• apache2 or httpd — Apache web server
• mysql or mariadb — MySQL/MariaDB database
• postgresql — PostgreSQL database
• ufw — UFW firewall service
• cron — cron job scheduler

Debugging a Failed Service

# Check status for clues
sudo systemctl status myapp

# Read the full journal log for the service
sudo journalctl -u myapp -n 100 --no-pager

# Try starting it manually to see errors in real time
sudo systemctl start myapp
sudo journalctl -u myapp -f

Creating a Simple Custom Service

Save a file to /etc/systemd/system/myapp.service:

[Unit]
Description=My Node App
After=network.target

[Service]
User=www-data
WorkingDirectory=/var/www/myapp
ExecStart=/usr/bin/node server.js
Restart=always

[Install]
WantedBy=multi-user.target

sudo systemctl daemon-reload
sudo systemctl enable --now myapp