> I can't think of a single good thing about using Tclunk to drive the ctl > state machine.
i can. it's the simplest way of doing things, works smoothly with existing stuff (e.g. echo blah > ctl), and would be just fine if the control request is never likely to fail, and performance isn't an issue. i've used russ's method of "zero-length write if you care about the result" before, and that works well, but i have to say i usually just ended up using cat or cp (i.e. ignoring errors). for another way, look at the way cdfs(4) lets you fixate disks. it's a little odd, but it works.
