Can I make do-release-upgrade only download packages for a later upgrade?

I'm running lubuntu 10.10, and would like to upgrade to 11.04. I have a very temperamental internet connection, so I would like to download all the packages before running the install.

According to this, there is no easy way to do this. The bug report mentioned in that thread is still open.

My question: Is there a way to hack do-release-upgrade to only download the packages, kind of like adding a "-d" to apt-get dist-upgrade?

Or is doing it manually the only way to get the result I desire?

If I have to do it manually, are these the steps needed to do it, or am I missing something?

1. Disable 3rd party repositories in /etc/apt/sources.list and /etc/apt/sources.list.d
2. Change repositories in /etc/apt/sources.list from maverick to natty
3. run sudo apt-get update
4. run sudo apt-get -d dist-upgrade to only download the packages. Do this as many times as necessary until all the packages are downloaded.
5. run sudo apt-get dist-upgrade to complete the upgrade process

Your first four steps are correct, but step 5 should be sudo do-release-upgrade (instead of sudo apt-get dist-upgrade). It should notice that all (or most) of the packages it was going to download are already present in /var/cache/apt/archives.

In some earlier versions of do-release-upgrade there was a bug where it would clean /var/cache/apt/archives before downloading the packages anew, but IIRC that bug's been fixed.

I wrote a script to do this, for my own upgrade of multiple machines to Ubuntu 14.04 "trusty". It is called 'apt-get-other-release'. Simple use:

$ sudo apt-get-other-release -t trusty
  [ a long time passes as it downloads stuff ]
$ sudo apt-get-other-release -U
  [ it prepares the system for upgrade -- this is quick ]
$ sudo do-release-upgrade   # or update-manager, whatever you're comfortable with
  [ upgrading also takes a long time and may still download some additional stuff ]

The script is at:

ftp://www.lubkin.com/pub/user/filbo/apt-get-other-release

and version 1.0 has sha1sum: 87a466b2bb2d1ac5b0a08509246a450b8d1c7617

Behind the scenes it's basically running apt-get update; apt-get -d dist-upgrade with its own private set of sources.list files. Results are stored in /var/cache/apt-$to_rel/archives, and the '-U' flag copies those into system-wide /var/cache/apt/archives so that they will be present during your upgrade.

You could also copy the upgrade archive from one local host to another, saving bandwidth. I did this for an amd64 and an i386 upgrade, copying only those *.deb which didn't have "amd64" in their names; then ran another apt-get-other-release -t trusty on the i386 machine, which downloaded another large pile of packages since the two machines had different stuff installed on them.

Feedback appreciated; email cc appreciated, as I don't know when I will next look at askubuntu. Search engines are well aware of me.

NOTE: I have not actually done an upgrade of a system so-treated! Some time in the next week. Getting this script out while it might be of some use to people.

>Bela<