Hi, One point of my bug report is that what you're trying to do (examine a block device for the content stored on it) is not anything new. We've been doing this for many many years and the way to do it is SUBSYSTEMS=="block", ACTION=="add|change", <more checks here>, <import/run etc here> and this is not something that "needs testing" or needs to be second-guessed or (dare I say) even tested since it's such a fundamental operation in how udev and the kernel works. Then there's the thing that the existing rules are obviously run - for example it really makes no sense anywhere to run programs accessing a device node on a "remove" event. That said, I do appreciate that you are testing things (we all should be testing more, really) but please realize that "success" or "failure" rarely means anything absolute when it comes to event driven system - often means that you just either hit or avoided some race condition :-) David