I was thinking of doing something like that, but there were a couple of reasons I decided against it.

Firstly, it makes the temporary files (more) predictable, which makes it easier to exploit the script (I know if everything else is handled properly this shouldn't be a problem, but you can never be too paranoid careful).

Also, the script is a fairly small utility and I'd like to make it as self-contained as possible. Having a cleanup script run via cron is a bit overkill for this.

From what I've been reading about %SIG, it looks like the right solution. I'll post something if I figure out a nice solution.