Thanks Peter, that does make more sense. As to the why: I'm writing a program that runs many different (but similar) programs and does stuff with the output. Most of the programs (exe) print to stdout: exe <input > output so I can open a pipe on exe <input and deal with the output directly. there are some that don't print to standard out: exe input produces output files that I read in. I went in thinking I could just use the same pipe interface for everything and then read other files afterward. I ran into problems (which I still haven't nailed down) and that's how I end up with this question. D