I've got it working now, using the integer file ids (0 for stdin, 1 for stdout, etc.) directly. I'm hoping to avoid using a tempfile, as this wrapper needs to be capable of distributing quite large (50-150MB) binaries with the Ruby code, and I don't want to copy them any more times than necessary. Now I'm working on adding the script's dependencies; my current prototype does some hackish things with the DATA filehandle and Marshal, but it seems to be working for trivial examples, at least. Thanks all, Lennon rcoder.net