I would like to know the specifics of exactly what happens when doing an apt-get update.
What files are downloaded from the websites listed in sources.list and were are they put? Are there separate lists for each repository saved to the local disk? The more information the better (exact file locations, step by step of what happens would be great!) I'm writing an application to help dialup users update Ubuntu and would be downloading the package lists and would need to replace the ones on Ubuntu with the ones the application downloads because all the files will be downloaded and saved onto a USB drive from another computer and will need to update the Ubuntu installation they are intended for.