With multiple Ubuntu machines in the house, it can be a pain to continually download the same updates over and over again. That’s why this post is quite useful with its tips on how to cache the updates in one place and have the other PCs point to that cache.
I’ve got it up and running – the key line being
echo 'Acquire::http::Proxy "http://hostname:3142";' | sudo tee /etc/apt/apt.conf.d/01proxy
but I have yet to confirm that it’s working.