Start at Boot

To start the Sprocket software at boot, we must create a Unix service using the systemd System and Service Manager.

Create a Launch Script

The launch script will reside in the user home directory and will launch a named screen session and then launch the Sprocket Python code.

In an SSH session, navigate to the user home directory using cd ~.
In your favorite text editor, create a file named start_sprocket.sh with the following contents:
```
#!/bin/sh
screen -dm -S sprocket python ~/Sprocket/main.py
```
Set the start_sprocket.sh script as executable using the chmod command:
```
chmod +x start_sprocket.sh
```
Test that the script works by launching it.
```
./start_sprocket.sh
```

Create a Systemd service

Now that we have our launch script, create a systemd service.

Navigate to the systemd system directory /lib/systemd/system
```
cd /lib/systemd/system
```

In your favorite text editor, as sudo, create a file named sprocket.service with the following contents:

[Unit]
Description=Run Sprocket on boot
After=multi-user.target

[Service]
ExecStart = /home/pi/start_sprocket.sh
RemainAfterExit=yes
User=pi

[Install]
WantedBy=multi-user.target

Reload the systemctl daemon.
```
sudo systemctl daemon-reload
```
Register the Sprocket service.
```
sudo systemctl enable sprocket.service
```

Check that the service is enabled.

sudo systemctl list-unit-files | grep sprocket

Manually start the service.
```
sudo systemctl start sprocket.service
```

Now, the Sprocket code will automatically start whenever the system is rebooted. To connect to the screen session to interface the program, use the screen -r command.

Debugging Systemd service

To check the status of the service, use the sudo systemctl status sprocket.service command.