Block a package from being uninstalled in APT

Question

In short, I want to be able to set package abc so that:

1. apt-get remove abc should fail.
2. apt-get purge abc should fail.
3. apt-get upgrade abc should work.

If the package dependencies change so that abc should be uninstalled during an dist-upgrade I am happy to being forced to do something and then dist-upgrade again.

Answer 1

Not really anything to 'pin' a package down to be able to prevent removal, but allow upgrading.

You can hammer a spike into a package, can't be deleted, purged, upgraded, licked, anything...

But it's a wee bit more complicated than most things.

For example, we wish to pin firefox down: (you'd use the proper full name of the package, of course)

echo firefox hold | dpkg --set-selections

which would then make 'firefox' immortal. BUT, it cannot be upgraded in this state either.

To remove the hold status is a bit easier, but it's kind of a sweeping gesture:

dpkg --clear-selections

removes the HOLD status from EVERYTHING! So if you wanted to hold a few packages, you'd best keep a list to reapply later

It's actually quite pleasant and easy to perform using aptitude or synaptics, as they have menu options to hold/unhold a package, taking care of all the bookkeeping behind the scenes for you. I'd recommend using one of those (or any of a myriad other package managers you might encounter)

With Aptitude, command line usage is possible too:

aptitude hold <package>
aptitude unhold <package>

Remember though, you'll need to 'unhold' something if want it to upgrade. Although if you use the GUI side of Aptitude, it should tell you if something that's held is upgradable