systemd cheatsheet

Service control

Command	Description
`systemctl start nginx`	Start a service now
`systemctl stop nginx`	Stop a service
`systemctl restart nginx`	Stop then start
`systemctl reload nginx`	Reload config (if supported)
`systemctl status nginx`	State, PID, recent log lines
`systemctl enable nginx`	Start at boot
`systemctl disable nginx`	Do not start at boot
`systemctl is-active nginx`	Print active/inactive (scripts)
`systemctl is-enabled nginx`	Print enabled/disabled

Listing units

Command	Description
`systemctl list-units --type=service`	Loaded services
`systemctl --failed`	All failed units (triage)
`systemctl list-units --state=failed`	Same, explicit filter
`systemctl reset-failed`	Clear failed state after fix
`systemctl list-unit-files`	All installed unit files
`systemctl list-timers --all`	Active and inactive timers
`systemctl show nginx`	All properties of a unit

Journal logs

Command	Description
`journalctl -u nginx`	Logs for a unit
`journalctl -u nginx -f`	Follow unit logs
`journalctl -u nginx --since today`	Logs since midnight
`journalctl -b`	Logs from current boot
`journalctl -p err -b`	Error-level messages this boot
`journalctl --disk-usage`	Journal space used

Unit file management

Command	Description
`systemctl cat nginx`	Show effective unit file
`systemctl edit nginx`	Create drop-in override
`systemctl daemon-reload`	Reload unit files after changes
`systemd-analyze verify my.service`	Validate unit syntax

Boot analysis

Command	Description
`systemd-analyze`	Total boot time
`systemd-analyze blame`	Time per unit at boot
`systemctl get-default`	Current default target
`systemctl isolate rescue.target`	Switch to rescue target

Minimal service unit example

# /etc/systemd/system/myapp.service
[Unit]
Description=My Application
After=network.target

[Service]
Type=simple
User=deploy
ExecStart=/opt/myapp/bin/server
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target

Pro tips

Always run systemctl daemon-reload after editing unit files
systemctl status shows the last few log lines — use journalctl -u for full history
enable does not start; start does not enable — set both for production
Use systemctl edit instead of editing files under /usr/lib/systemd/

Practice scenarios

Hands-on systemd scenarios on live Linux VMs: systemd