[Haskell-cafe] trying to understand runProcess handles

[Donn Cave]

On Thu, 2 Mar 2006, Matthias Fischmann wrote:
...
> The problem is that gnuplot terminates right away after it tries to
> read from stdin (I can see the shadow of a window appear and vanish
> immediately).  I tried setFdOption, with no effect.  Is this because
> the handles passed to runProcess are closed in the parent process, and
> therefore the pipe is teared down and useless?
> 
> I don't think so: If I run 'find /' instead of gnuplot, the process
> happily starts and I can hGetLine from stdout.

That doesn't necessarily disprove your hypothesis, since "find" doesn't
read input.  You might try "tr" instead, for example.  I don't see
anything about what you were doing that would be obviously different
from runProcessInteractive, but as long as you're making a pipe for
error output, you may as well read it and see if gnuplot has left
any clue to its problem there.

	Donn Cave, donn at drizzle.com