I asked a regex question over at SO. Someone answered with a ruby solution. I'm pretty sure it can be done with GNU tools. I remembered seeing all the cool things here when snooping around area51. Is it alright to ask that question here?
My point of view is you shouldn't be asking here because you're trying to get help. You should ask here if you know the problem presents a interesting challenge in some way.
This will be very hard to police: we're basically relying on you to police yourself.
Of course, there must exist the corner case, and I'd say "on-topic" for those.