Hi, I have Ubuntu at home on my desktop computer but I have no access to the Internet. I'm writting from a University campus. I'd like to know if I can update my Ubuntu using an USB Flash key. How can I update my Ubuntu without a direct connection to the Internet?
Thanks,

The easiest way would be to just wait for the latest Ubuntu release, download the ISO, and update that way. Ubuntu will recognize the new Ubuntu version as soon as you put the CD in the drive and ask you if you want to update your system to this version. I only used it once or twice in the past, but I never had problems with it.

Beyond that, you could download the individual packages you need, save them to a USB flash drive, and then install them when you get back to your Ubuntu machine. But the problem there would be figuring out exactly which ones you need, and then of course the tedious process of downloading them all manually.

There is probably a better way to do it, but somebody with more Ubuntu experience would need to fill in the blanks there.

It would be pretty tough to figure out what packages have updates without a connection. First you have to set up repositories in your /etc/apt/sources.list, then with an internet connection you have to issue command:

sudo apt-get update

To get package information from all your repositories in the /etc/apt/sources.list which should have an entry for updates. Then you would open up Synaptic and on the left there should be some sub categories of packages like "Installed, Not installed, Installed upgradeable", the Installed upgradeable list will tell you which version of package that has an update and the updated package version available.
If you can somehow get that list, then you should be able to download the packages from the URL in the update source in /etc/apt/sources.list onto a pen/thumb drive and make a directory in /home or /opt or separate data partition (wherever) and add that directory to your /etc/apt/sources.list and go back to Synaptic which will still have the same list of updates even if it was taken off-line and mark all the packages you acquired and select "Apply". Synaptic will refer to your local repository first. You can also probably put the packages in /var/cache/apt/debs without making a separate local entry in the /etc/apt/sources.list.
Here is a link to help setting up sources.list:

http://ubuntuguide.org/wiki/Ubuntu_E...a_repositories

PS:

Updating is actually not really needed for the average home computer user, it is more of a great deal for a server that can't afford intrusions and the likes. Everybody feels they need to be fully updated but don't actually know why? Most home computer users don't have anything to worry about if their distribution is an "Official" or "Final" release version as these are usually pretty stable and usually work flawlessly without tampering. Some distributions do have issues, like my Fedora where there was a lot of bugs that affected some users with certain hardware. But I personally don't think you have much to worry about with a Debian distribution, especially if they follow Debian's roll model. If you do have something not working properly on your system, just try and figure out which package is giving the problems and go directly to the update site listed in the link I gave in the prior post to see if there is an update for that package by comparing the version number to the one installed and download it and install it from the pen drive with command:

dpkg -i /media/pen_drive/package_name

Or dpkg -u, for update, not sure as I'm in Fedora right now but read the man page for dpkg.

I have moved this to the Ubuntu forum as it's more suited there than here