Creating a Custom Systemd Service
Creating a systemd service involves writing a service unit file and configuring it so that systemd can manage your service. Here’s how you can create a custom service in Linux using systemd.
Steps to Create a Service
1. Create a Service Unit File
Service unit files for systemd are stored in /etc/systemd/system/ (for custom services) or /lib/systemd/system/ (for system-provided services).
-
Open a terminal and create a new service file under
/etc/systemd/system/:sudo nano /etc/systemd/system/my-custom-service.serviceReplace
my-custom-service.servicewith the name of your service.
2. Define the Service Configuration
The service file contains metadata and instructions about how the service should run. Here’s a basic template for a service:
[Unit]
Description=My Custom Service
After=network.target
[Service]
ExecStart=/path/to/your/script-or-program
Restart=always
User=myuser
WorkingDirectory=/path/to/working-directory
[Install]
WantedBy=multi-user.target
- [Unit] Section:
Description: A brief description of the service.After=network.target: Ensures the service starts after the network is up. You can adjust this to suit your needs.
- [Service] Section:
ExecStart: The command to start your service. This could be a script, a binary, or any command you want to run as a service.Restart=always: Tellssystemdto always restart the service if it crashes or stops.User=myuser: Run the service as a specific user (replacemyuserwith the actual user).WorkingDirectory: The directory where the service should be executed.
- [Install] Section:
WantedBy=multi-user.target: This tellssystemdthat the service should be enabled in multi-user mode (the usual mode for non-graphical systems).
3. Save and Close the File
After defining the service configuration, save the file and exit (Ctrl + X, then Y, then Enter in nano).
4. Reload systemd to Apply the New Service
To make systemd recognize the new service, reload the systemd daemon:
sudo systemctl daemon-reload
5. Start and Enable the Service
Now, you can start the service:
sudo systemctl start my-custom-service
To enable the service to start automatically on boot:
sudo systemctl enable my-custom-service
6. Check the Status of the Service
You can check the status of the service to see if it’s running correctly:
systemctl status my-custom-service
7. View Logs for the Service
If your service encounters issues, you can view its logs using journalctl:
journalctl -u my-custom-service
Example: Running a Python Script as a Service
If you have a Python script (/home/myuser/myscript.py) and want to run it as a service, your service file might look like this:
[Unit]
Description=Run My Python Script
After=network.target
[Service]
ExecStart=/usr/bin/python3 /home/myuser/myscript.py
Restart=always
User=myuser
WorkingDirectory=/home/myuser
[Install]
WantedBy=multi-user.target
Summary of Commands
- Create the service file:
sudo nano /etc/systemd/system/my-custom-service.service - Reload
systemd:sudo systemctl daemon-reload - Start the service:
sudo systemctl start my-custom-service - Enable the service at boot:
sudo systemctl enable my-custom-service - Check the service status:
systemctl status my-custom-service
Once these steps are completed, your custom service will be created and managed by systemd, and you can start, stop, and enable it like any other system service.
To delete a service that you created and registered with systemd, follow these steps:
1. Stop the Service
First, stop the service if it’s currently running:
sudo systemctl stop <service-name>
Replace <service-name> with the actual name of your service (without the .service extension).
2. Disable the Service
Disable the service to prevent it from starting automatically at boot:
sudo systemctl disable <service-name>
This removes any symbolic links created by systemd that link the service to system startup.
3. Delete the Service File
Find and delete the service file that you originally created. Typically, custom service files are placed in one of the following directories:
/etc/systemd/system//lib/systemd/system/
To remove the service file, run:
sudo rm /etc/systemd/system/<service-name>.service
or
sudo rm /lib/systemd/system/<service-name>.service
Make sure you are deleting the correct service file.
4. Reload systemd Daemon
After deleting the service file, you need to reload systemd to inform it of the change:
sudo systemctl daemon-reload
This command forces systemd to reload its configuration files and reflect the removal of the service.
5. Remove Service-Related Files (Optional)
If your service involved additional files like logs, environment files, or configuration files, you might also want to delete them. For example, if you had log files in /var/log/ or configuration files under /etc/, you can manually remove them.
By following these steps, you will have completely removed the service from your system. If you want to confirm that it’s gone, you can check the service status:
systemctl status <service-name>
This should return an error indicating that the service file no longer exists.
