Systemd is a system and service manager for Linux. It provides a standard process for controlling what programs run when a Linux system boots up. However, there might be instances when a systemd service does not start at boot. This article will guide you through the troubleshooting steps to identify and resolve the issue.
Understanding Systemd Services
Systemd services are defined by service unit files. These files contain information about the service including how to start, stop, and restart the service, and under what circumstances it should automatically start at boot.
A typical service file might look like this:
[Unit]
Description=My Custom Service
After=network.target
[Service]
ExecStart=/usr/local/bin/my-service
User=myuser
Restart=always
[Install]
WantedBy=multi-user.targetIn this example, the ExecStart directive specifies the command to run to start the service. The User directive specifies the user to run the service as, and the Restart directive tells systemd to always restart the service if it stops. The WantedBy directive in the [Install] section tells systemd to start the service when the system reaches the multi-user.target, which is the standard runlevel for multi-user systems.
Checking the Service Status
The first step in troubleshooting a service that is not starting at boot is to check its status. You can do this with the systemctl status command:
systemctl status my-serviceThis command will show you whether the service is currently running, and if not, why it stopped. Look for any error messages or other information that might indicate why the service did not start.
Checking the System Logs
Next, you should check the system logs for any error messages related to your service. You can do this with the journalctl command:
journalctl -u my-serviceThe -u option tells journalctl to only show logs for the specified unit (in this case, my-service). Look through the logs for any error messages or other information that might help you understand why the service is not starting.
Verifying the Service File
If the service status and logs do not provide any clues, the next step is to verify the service file itself. Check that the ExecStart directive points to a valid executable, and that the User directive specifies a valid user. Also, check that the WantedBy directive in the [Install] section is set to multi-user.target or another appropriate target.
Checking for Conflicting Services or Dependencies
Another possible cause of a service not starting is a conflict with another service, or a missing dependency. You can check for these issues with the systemctl list-dependencies command:
systemctl list-dependencies my-serviceThis command will show you all the other units that your service depends on, and whether they are currently active. If any of the dependencies are not active, you will need to investigate why.
Conclusion
Troubleshooting a systemd service that is not starting at boot can be a complex task, but by following these steps, you should be able to identify and resolve the issue. Remember to check the service status, system logs, service file, and dependencies, and don’t hesitate to seek help from the community if you’re stuck.
You can check the status of a systemd service by using the command systemctl status [service-name]. This will display information about the service, including whether it is currently running or not.
To restart a systemd service, you can use the command systemctl restart [service-name]. This will stop and then start the service again.
To enable a systemd service to start at boot, you can use the command systemctl enable [service-name]. This will create the necessary symlinks to ensure the service starts automatically when the system boots up.
Yes, you can view the logs for a specific systemd service by using the command journalctl -u [service-name]. This will display the logs related to that service only.
You can check the dependencies of a systemd service by using the command systemctl list-dependencies [service-name]. This will show you all the units that the service depends on, as well as their current status.
