Stop the Petio service.
sudo systemctl stop petio
Download the latest version of Petio.
sudo wget https://petio.tv/releases/latest -O petio-latest.zip
Extract to petio folder.
sudo unzip petio-latest.zip -d /opt/Petio
Start Petio service.
sudo systemctl start petio
Remove the file you downloaded so you are ready for a new update later on.
sudo rm petio-latest.zip