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I have a computer running Ubuntu 7.04 that for various reasons cannot
have an internet connection. However, I am able to download files
elsewhere and copy them over using a USB flash drive. I'm already
familiar with making local repositories and manually installing .deb
files, but the part that I have yet to discover is how to update the
package list that Synaptic/apt-get uses when it decides what is
available. I know it has something to do with the Packages.gz file
that gets downloaded from each repository, but is there a way to
download those myself and then get Synaptic to recognize the local
versions as if they had really come from the internet sites? This
would allow me to still use the trick of asking Synaptic to install
them, dumping the error log into a file when it can't establish the
connections to the repositories (no internet connection) and then
turning that error log into a download list for the other computer to
grab the files from the correct sites, including all dependencies.
Take these fresh files, stick them in the /var/cache/apt/archive
directory, and then Synaptic thinks that it has already downloaded
them and just goes ahead and installs them anyway. Does anyone know
how to fake an update to the package list that Synaptic/apt-get uses?

I don't want to create a local mirror of the internet repositories
since that would take up WAY too much space. Instead I want to take
the information from the package list files (Packages.gz) and fake
whatever happens behind the scenes when I press the reload button in
Synaptic or run "apt-get update". I still want Synaptic to think that
it will download from the internet sites when I hit the apply button.
To further complicate things, the computer that will actually have the
internet connection (which CANNOT be shared with the Ubuntu machine)
will be Windows XP based... So most scripts and Linux based programs
will be non-starters. I can manually download files and do some
parsing/fineseing by hand. Anything that Firefox and a nice text
editor can handle. Not much beyond that.
Any takers?
-Will

My evil plan:
1) Download the Packages.gz files from a bunch of internet
repositories
2) * Merge the info from the Packages.gz files into apt-get/Synaptic
3) Ask Synaptic to download the .deb packages that I want to install
4) Capture the error log to determine the exact URLs that apt-get was
trying to connect to for each package
5) Manually download the packages each URL points to and transfer to
the unconnected computer
6) Place the packages in the /var/cache/apt/archives/ directory
7) Ask Synaptic to install the packages, which it now can do because
they already exist locally
8) ????
9) Profit!!

I have already done everything except 2, 8, and 9 so I know it works.