systemd Cheat Sheet — systemctl Commands Reference Free

Complete systemd and systemctl command reference. Start, stop, enable, check status, view logs with journalctl, write unit files. Free Linux sysadmin reference.

Service Management

systemctl start nginx

Start a service immediately

systemctl stop nginx

Stop a running service

systemctl restart nginx

Restart a service (stop + start)

systemctl reload nginx

Reload config without full restart

systemctl status nginx

Show service status and recent logs

systemctl enable nginx

Enable service to start at boot

systemctl disable nginx

Disable service from starting at boot

systemctl enable --now nginx

Enable AND start immediately

systemctl is-active nginx

Check if service is active (exit code 0=yes)

systemctl is-enabled nginx

Check if service is enabled at boot

systemctl mask bluetooth

Completely disable (prevents manual start too)

systemctl unmask bluetooth

Remove mask from service

systemctl list-units --type=service --state=active

List all active service units

systemctl list-unit-files --type=service

List all installed unit files + their state

systemctl daemon-reload

Reload systemd after editing unit files

systemctl edit nginx

Edit service override (drop-in config)

systemctl cat nginx

Show unit file and all overrides

systemctl show nginx --property=MainPID

Show all unit properties

Viewing Logs (journalctl)

journalctl -u nginx

Show all logs for a unit

journalctl -u nginx -f

Follow/tail logs for a unit

journalctl -u nginx -n 100

Show last 100 log lines

journalctl -u nginx --since today

Show logs since midnight

journalctl -u nginx --since "1 hour ago"

Show logs from last hour

journalctl -u nginx -p err

Show only error-level messages

journalctl -u nginx --no-pager | grep 502

Output without pager (pipe-friendly)

journalctl -b

Show logs from current boot

journalctl -b -1

Show logs from previous boot

journalctl --list-boots

List all available boots

journalctl -k --since "10 min ago"

Show only kernel messages (dmesg)

journalctl --disk-usage

Show how much disk space logs use

journalctl --vacuum-size=500M

Reduce log storage to 500MB

System State

systemctl poweroff

Power off the machine

systemctl reboot

Reboot the machine

systemctl suspend

Suspend to RAM

systemctl hibernate

Hibernate to disk

systemctl rescue

Enter rescue mode (single user)

systemctl emergency

Enter emergency mode (minimal)

systemctl get-default

Show default target (runlevel)

systemctl set-default multi-user.target

Set default target to multi-user (no GUI)

systemctl isolate graphical.target

Switch to graphical target now

systemctl list-dependencies nginx

Show unit dependency tree

Timer Units

systemctl list-timers --all

List all active timers with next/last run

systemctl start backup.timer

Start a timer unit

systemctl enable backup.timer

Enable timer at boot

journalctl -u backup.service

View logs for timer-triggered service

Unit File Structure

# /etc/systemd/system/myapp.service
[Unit]
Description=My Application
Documentation=https://example.com
After=network.target          # Start after networking
Requires=redis.service        # Hard dependency
Wants=postgresql.service      # Soft dependency

[Service]
Type=simple                   # simple|forking|oneshot|notify
User=deploy                   # Run as this user
Group=deploy
WorkingDirectory=/var/www/myapp
ExecStart=/usr/bin/node server.js
ExecReload=/bin/kill -HUP $MAINPID
ExecStop=/bin/kill -TERM $MAINPID
Restart=on-failure            # always|on-failure|no
RestartSec=5                  # Wait 5s before restart
StandardOutput=journal        # Log stdout to journal
StandardError=journal
SyslogIdentifier=myapp        # Tag in journal logs
Environment=NODE_ENV=production
EnvironmentFile=/etc/myapp.env  # Load env vars from file
LimitNOFILE=65536             # Increase open file limit
TimeoutStartSec=30
TimeoutStopSec=10

[Install]
WantedBy=multi-user.target    # Enable target (like runlevel 3)

After creating/editing: systemctl daemon-reload && systemctl enable --now myapp.service

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Frequently Asked Questions

How do I use the systemd Cheat Sheet?

Browse by task (start service, check logs, write unit file) or search by command. Each entry shows the exact command with explanation.

Is the systemd Cheat Sheet free?

Yes, systemd Cheat Sheet on ToolPix is 100% free with no signup or installation required.

Is my data safe?

This is a static reference tool. No data is entered or transmitted.

How do I start a service and enable it on boot?

sudo systemctl start myservice — starts it now. sudo systemctl enable myservice — starts it on boot. Combine: sudo systemctl enable --now myservice.

How do I view service logs?

journalctl -u myservice shows all logs for a service. Add -f to follow in real time, -n 50 for last 50 lines, --since '1 hour ago' to filter by time.

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