Raspberry Pi; Working with systemctl

Ervinator Updated on

Working with systemctl on a Raspberry Pi is similar to working with any other Linux system that uses the systemd init system. systemctl is the command-line interface for interacting with systemd, allowing you to manage services, check their status, enable or disable them, and more. Below are some common tasks and commands you’ll find useful when working with systemctl on a Raspberry Pi.

Common systemctl Commands

1. Check the Status of a Service

To check the status of a specific service, use: 
sudo systemctl status myservice.service

Replace myservice.service with the name of the service you want to check.

2. Start a Service

To start a service immediately, use: 
sudo systemctl start myservice.service

3. Stop a Service

To stop a running service, use: 
sudo systemctl stop myservice.service

4. Restart a Service

To restart a service, which stops it and then starts it again, use: 
sudo systemctl restart myservice.service

5. Enable a Service at Boot

To enable a service to start automatically at boot, use: 
sudo systemctl enable myservice.service

6. Disable a Service from Starting at Boot

To prevent a service from starting automatically at boot, use: 
sudo systemctl disable myservice.service

7. List All Services

To list all services and their statuses, use: 
systemctl list-units --type=service

8. List Enabled Services

To see only the services that are enabled to start at boot, use: 
systemctl list-unit-files --type=service --state=enabled

9. View Logs for a Service

To view logs related to a specific service, use journalctl: 
sudo journalctl -u myservice.service

Note: Use your arrow keys up [ 🠉 ] and down [ 🠋 ] to navigate. Use [ Q ] to leave.

You may have noticed, that the previous command returned older data, but you may expect to see the new data first, right? Use -r to reverse the output: 
sudo journalctl -u myservice.service -r
You can add --follow to view logs in real-time: 
sudo journalctl -u myservice.service --follow

10. Check System Boot Logs

To view logs related to the system boot process, you can use: 
journalctl -b

Managing Services on Raspberry Pi

Creating a Custom Service

If you need to create your own service (like a Python script), follow these steps:

1. Create the Service File: 
sudo nano /etc/systemd/system/mycustom.service
Add the following content:
ShellScript
[Unit]
Description=My Custom Service
After=network.target

[Service]
ExecStart=/usr/bin/python3 /home/pi/myscript.py
WorkingDirectory=/home/pi
StandardOutput=inherit
StandardError=inherit
Restart=always

[Install]
WantedBy=multi-user.target

Adjust the ExecStart line to point to your script and interpreter.

2. Reload systemd: 
sudo systemctl daemon-reload
3. Start and Enable the Service: 
sudo systemctl start mycustom.service
sudo systemctl enable mycustom.service

Note: Skip the systemctl enable command, if you don’t want to run your script every time the pi boots.

Summary of Important Commands

  • Start a Service: sudo systemctl start myservice.service
  • Stop a Service: sudo systemctl stop myservice.service
  • Restart a Service: sudo systemctl restart myservice.service
  • Enable a Service at Boot: sudo systemctl enable myservice.service
  • Disable a Service from Boot: sudo systemctl disable myservice.service
  • Check Service Status: sudo systemctl status myservice.service
  • View Logs: sudo journalctl -u myservice.service

Additional Tips

  • Use sudo for commands that require administrative privileges.
  • Always check the syntax of your service files carefully; errors can prevent the service from starting.
  • Use systemctl list-dependencies to see what services are dependent on others, which can help in troubleshooting.

Now that you are familiar with the basic systemctl and journalctl commands, let’s create your very own custom service!