Unmet dependency solution in Synaptic
Most Linux users have an ugly Pavlovian response to the phrase “unmet dependencies”. Because I use a distribution that coddles me to a (sometimes unhealthy) extreme, I had forgotten about the frightening package dependency jumbles that I used to get into when I used Fedora Core 3.
I reformatted my laptop’s hard drive in order to switch to XFS. [0] As with all installations that I don’t have time to automate, I end up making the same little tweaks I always make in slightly different ways. In tweaking the font clarity, however, I got a bit carried away, and started reading about code that (purportedly) improved font quality dramatically, but hadn’t made it into the Feisty version of the Ubuntu distribution.
I (stupidly) installed a third party package instead of searching around for other options first. The result was some mild package mayhem.
Here’s a short description of how to go about solving a problem similar to this one using Synaptic (the GUI manager for dpkg systems):
- Track the dependency chain down to the first conflicting package. You’ll get messages like “This package [you're trying to install] depends on X, but X isn’t going to be installed.” X is your new target, for each X, iteratively.
- Try to force the package to the official version (Ctrl+E). You’ll likely get more messages like in 1. If you do, GOTO 1. Otherwise, move on to 3.
- End up at a (most reduced) conflicting package. You’ll get a message that says, “This whole mess of applications will have to be removed.” If you get this, you’ve found one of the most reduced conflicting packages. In this case I found it to be libfreetype6. I couldn’t force libfreetype6, because there were very important packages (e.g. ubuntu-desktop) that depended on upgraded packages that depended on this new version of libfreetype6. You can view dependent packages via the package properties that Synaptic displays; however, you don’t see what version they are dependent on (I’ll submit a feature request in a few days). As a result, your best bet is to search for dependent packages via Synaptic’s search feature.
- Knock off 3rd party dependent packages by forcing them to the official version. Be wary of removing a lot of important things by accident in the process! If it has a slew of applications “to be removed”, try forcing other dependent packages to the official version first.
- Work your way back down to the more shared packages by forcing versions up the dependency tree. Once you force less-shared packages to official versions or prune off unnecessary packages, you should be able to start forcing more-shared packages to official versions. This is a natural result of having less unofficial stuff to support dependencies for!
[0] I thought that the potential performance benefits of a metadata-only journaling filesystem were intriguing, and I hoped that it would alleviate some of the degradation that I encounter running a 5400rpm drive.
NOTE: This entry is sloppily written in a stream-of-conscious style, but I don’t really have much time to edit it. Sorry!
Tags: Package Management, Synaptic