E.g. Ubuntu Server offers only security updates for software contained in the main repository - how can I check, which installed packages are / are not in the main repo? Thanks!
I can't find an answer to this anyplace.
How often are the repository mirrors updated?
Are they really all the same as the main server?
Do they automatically check the main repo for new files every five minutes? hour? day?
I'm looking for information on whether there is an easier way to do this. I have set up a company repo, we use custom packages for a few items. What I want to avoid is this package being installed or updated from another repo (base, extras, updates, or any other repo that is installed).