The systemctl command is the main interface for controlling systemd units.

Units include:

• Services (.service)
• Timers (.timer)
• Sockets (.socket)
• Targets (.target)
• Mounts (.mount)

Overview

Typical administrative tasks include:

• Starting and stopping services
• Enabling services at boot
• Checking status and failed units
• Reloading configuration
• Managing user and system instances

Syntax

systemctl [command] [unit]

Command Quick Reference

Command	Purpose
systemctl status <unit>	Show service status and recent logs
systemctl start <unit>	Start a unit
systemctl stop <unit>	Stop a unit
systemctl restart <unit>	Restart a unit
systemctl reload <unit>	Reload configuration without full restart (if supported)
systemctl enable <unit>	Enable at boot
systemctl disable <unit>	Disable at boot
systemctl is-active <unit>	Check if running
systemctl is-enabled <unit>	Check boot-enable state
systemctl daemon-reload	Reload unit files after changes
systemctl list-units --type=service	List active service units
systemctl --failed	List failed units

Core Workflows

Inspect Service State

sudo systemctl status ssh
systemctl is-active ssh
systemctl is-enabled ssh

Start, Stop, Restart

sudo systemctl start nginx
sudo systemctl stop nginx
sudo systemctl restart nginx

Reload Config and Unit Definitions

sudo systemctl reload nginx
sudo systemctl daemon-reload

Use daemon-reload after modifying files in /etc/systemd/system.

Enable or Disable on Boot

sudo systemctl enable nginx
sudo systemctl disable nginx

View Failed Units

systemctl --failed

Useful Options

Option	Meaning
--type=service	Restrict unit listing to services
--all	Include inactive units in lists
--no-pager	Print full output without pager
--user	Operate on user-level units
-l	Show full lines without truncation

Examples

sudo systemctl status ssh
sudo systemctl restart docker
systemctl list-units --type=service --all

Troubleshooting

Unit Not Found

1. Confirm unit name with systemctl list-unit-files | grep <name>.
2. If you added a new unit file, run sudo systemctl daemon-reload.
3. Use fully qualified unit names when needed (example: nginx.service).

Service Fails to Start

Check details with:

sudo systemctl status <unit>
sudo journalctl -u <unit> -n 200 --no-pager

Enable Fails Due to Missing Install Section

Unit file may not include an [Install] section, or may not be designed for enabling.

Best Practices

1. Prefer systemctl for service lifecycle control over manual process killing.
2. Use reload when possible to avoid unnecessary downtime.
3. Check status and related journal logs after changes.
4. Run daemon-reload after any unit file edits.
5. Use is-active and is-enabled in health checks and scripts.

Related Commands

• journalctl: Inspect service logs from systemd journal
• ps: Process-level inspection
• kill and pkill: Direct process signaling