I'm having some difficulties exactly understanding how the the whole update thing work in linux (Ubuntu) and good practice for installing software. I understand I have a /etc/apt/sources.list file where all my repositories are listed, and that these repositories are queried when I use apt-get update --to later be used with eg. apt-get upgrade. This makes perfect sense and I recently installed spotify by adding deb http://repository.spotify.com stable non-free to this "sources" list.
But then I got confused...
When I went to download google chrome I merely had to download and grab a .deb file, and chrome is installed with no problem...but...I don't see any new entry in /etc/apt/sources.list...so how does apt-get update know where to query concerning chrome updates? Has it somehow been added to one of the already listed repositories in the sources file?
I would like all my installed software to be encompassed by the update function.
Thanks a bunch for any help! :)