Re: [Haskell-cafe] Can't establish subprocess communication

(hin, hout, _, p) <- runInteractiveProcess "copierer" [] Nothing

./twowaysubprocesscomm twowaysubprocesscomm: fd:7: hGetLine: end of file twowaysubprocesscomm: fd:6: hPutChar: resource vanished (Broken pipe)

Because you didn't give the right path to copierer. And you should hSetBuffering in copierer.hs. Because the handles returned by runInteractiveProcess are actually pipes that connect to copierer's stdin and stdout.