[Haskell-cafe] Re: Execution of external command

Yitzchak Gale gale at sefer.org
Thu Dec 13 12:38:58 EST 2007

Bulat Ziganshin wrote:
>> ...are there any objections against...
>> (_, h, _, _) <- runInteractiveCommand "script params"
>> output <- hGetContents h
>> taking into account that bad-behaved scripts are not my headache?

"bad-behaved scripts are not my headache" is not the same
as "behave nicely". Or I guess they are the same - if they
don't behave nicely, then they are your headache whether
you like it or not. :)

Simon Marlow wrote:
> It could deadlock if the script produces enough stderr to fill up its pipe
> buffer

If we need to worry about that, then what about this:

(_,h,e,_) <- runInteractiveCommand "script params"
forkIO (hGetContents e >>= evaluate . length)
output <- hGetContents h

It requires -threaded in the case of a huge amount
of output to both stdout and stderr; maybe that isn't
good for Bulat. If that is a problem, you can read a chunk
at a time and call yield - but that is getting messier.


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