Use systemd to Start a Linux Service at Boot

Use systemd to Start a Linux Service at Boot

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What is systemd?Permalink

systemd is a Linux system tool initially developed by the Red Hat Linux team. It includes many features, including a bootstrapping system used to start and manage system processes. It is currently the default initialization system on most Linux distributions. Many commonly used software tools, such as SSH and Apache, ship with a systemd service.

It is simple to create a custom systemd service that will run any script or process you choose. Although there are several ways to run a script or start a process when your Linode boots, a custom systemd service makes it easy to start, stop, or restart your script, as well as configure it to start automatically on boot. systemd offers the advantage of using a standardized interface that is consistent across all Linux distributions that support it.

Create a Custom systemd ServicePermalink

  1. Create a script or executable that the service will manage. This guide uses a simple Bash script as an example:test_service.sh1 2 3 4 5 6 7 8 DATE=`date '+%Y-%m-%d %H:%M:%S'` echo "Example service started at ${DATE}" | systemd-cat -p info while : do echo "Looping..."; sleep 30; doneThis script will log the time at which it is initialized, then loop infinitely to keep the service running.
  2. Copy the script to /usr/bin and make it executable:sudo cp test_service.sh /usr/bin/test_service.sh sudo chmod +x /usr/bin/test_service.sh
  3. Create a Unit file to define a systemd service:/lib/systemd/system/myservice.service1 2 3 4 5 6 7 8 9 [Unit] Description=Example systemd service. [Service] Type=simple ExecStart=/bin/bash /usr/bin/test_service.sh [Install] WantedBy=multi-user.targetThis defines a simple service. The critical part is the ExecStart directive, which specifies the command that will be run to start the service.
  4. Copy the unit file to /etc/systemd/system and give it permissions:sudo cp myservice.service /etc/systemd/system/myservice.service sudo chmod 644 /etc/systemd/system/myservice.service For more information about the unit file and its available configuration options, see the systemd documentation.

Start and Enable the ServicePermalink

  1. Once you have a unit file, you are ready to test the service:sudo systemctl start myservice
  2. Check the status of the service:sudo systemctl status myservice If the service is running correctly, the output should resemble the following: ● myservice.service - Example systemd service. Loaded: loaded (/lib/systemd/system/myservice.service; enabled; vendor preset: enabled) Active: active (running) since Tue 2018-05-01 18:17:14 UTC; 4s ago Main PID: 16266 (bash) Tasks: 2 Memory: 748.0K CPU: 4ms CGroup: /system.slice/myservice.service ├─16266 /bin/bash /usr/bin/test_service.sh └─16270 sleep 30 May 01 18:17:14 localhost systemd[1]: Started Example systemd service.. May 01 18:17:14 localhost cat[16269]: Example service started at 2018-05-01 18:17:14 May 01 18:17:14 localhost bash[16266]: Looping...
  3. The service can be stopped or restarted using standard systemd commands:sudo systemctl stop myservice sudo systemctl restart myservice
  4. Finally, use the enable command to ensure that the service starts whenever the system boots:sudo systemctl enable myservice Created symlink from /etc/systemd/system/multi-user.target.wants/myservice.service to /lib/systemd/system/myservice.service.
  5. Reboot your Linode from the Linode Manager and check the status of the service:sudo systemctl status myservice You should see that the service logged its start time immediately after booting: ● myservice.service - Example systemd service. Loaded: loaded (/usr/lib/systemd/system/myservice.service; enabled; vendor preset: disabled) Active: active (running) since Wed 2018-05-02 15:03:07 UTC; 48s ago Main PID: 2973 (bash) CGroup: /system.slice/myservice.service ├─2973 /bin/bash /usr/bin/test_service.sh └─3371 sleep 30 May 02 15:03:07 localhost systemd[1]: Started Example systemd service.. May 02 15:03:07 localhost systemd[1]: Starting Example systemd service.... May 02 15:03:07 localhost bash[2973]: Looping... May 02 15:03:37 localhost bash[2973]: Looping...

More InformationPermalink

You may wish to consult the following resources for additional information on this topic. While these are provided in the hope that they will be useful, please note that we cannot vouch for the accuracy or timeliness of externally hosted materials.

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