systemctl: Managing systemd Services Correctly

Services fail to start, restart loops occur, or changes to unit files have no effect because systemd was not reloaded after editing.

Use the correct sequence of systemctl commands when creating or modifying services.

# Check service status with full log tail
systemctl status nginx.service

# Start, stop, restart
systemctl start nginx
systemctl stop nginx
systemctl restart nginx

# Reload config without full restart (if supported)
systemctl reload nginx

# Enable at boot
systemctl enable nginx

# Enable and start in one command
systemctl enable --now nginx

# After editing a unit file — MUST reload daemon
systemctl daemon-reload
systemctl restart myapp

# Show all failed services
systemctl --failed

# Mask a service (prevent it from being started)
systemctl mask apache2

systemd caches unit files in memory. Editing /etc/systemd/system/myapp.service has no effect until daemon-reload is called. This is the most common cause of 'my changes aren't taking effect'.