[Haskell-cafe] trying to understand runProcess handles
donn at drizzle.com
Fri Mar 3 12:05:49 EST 2006
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
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