The only thing I'd like to check on that I can't tell about is whether passing stdin and stdout to runProcess will behave "correctly". Some programs (e.g. gpg) can figure out how to get control of the tty by themselves (to ask for passwords in the case of gpg), but others (some versions of vi) will fail if their stdin and stdout correspond to a tty. It would be nice to be able to run "user-interactive" commands such as text editors in a safe and consistent manner. I'm not clear from your code whether there will be a problem with passing stdin and stdout to runProcess. If the process closes stdin, will it be closed for me? If the process changes the buffering of stdin, will that change it for me? Enquiring minds want to know! :)

Good questions, none of which I have given any thought to :-) You're almost certainly in a better position than me to decide what reasonable answers to these are, so would you like to propose some? Cheers, Simon