There should be a simple way of updating an ubuntu installation offline, and there should be a way in which computers can share updates.
Well there is apt-medium you could adopt. http://wiki.debian.org/AptMedium
On the mailing list, there were a number of suggestions. This one concerns sharing updates:
There was a reference to apt-zeroconf, putting forward this idea: "The idea is simple. On your home machines you check a box in the gui someplace, and then all your machines share their apt packages with each other. Which means that on release day you upgrade one machine, and then when you upgrade the others you don’t have to redownload everything again. Nice huh? Combine this with deb delta syncing and you’ve got a nice little bandwidth saving solution."
These ones concern offline updating:
- Synaptic has a "generate download script" option which spits out a script full of wgets that you could take to another net-connected machine to get the actual packages. I don't think it copes well if you want to update package lists or add further repositories sadly, but it's a start.
Also the suggestion was made that there might need to be an OS-independent way of getting updates (perhaps in a web-based way), so that you could get Ubuntu updates in a Windows-based internet cafe. (Keryx currently implements a lot of this: http://keryxproject.org)
Users could also use debmirror to create a partial mirror on an external hard disk where there is bandwidth available (such as a university, for example) - https://lists.launchpad.net/ubuntu-ngo/msg00117.html
Use Ubuntu Repositories from DVD - Get Iso file for Ubuntu Repository DVDs