Ubuntu updates

We do not want ubuntu updates to be running in the background. From time to time, this causes a pop-up "do you want to update this computer".

To turn this off, we change /etc/apt/apt.conf.d/10periodic

to

APT::Periodic::Update-Package-Lists "0";

See (https://www.garron.me/en/linux/turn-off-stop-ubuntu-automatic-update.html)