[Haskell-cafe] struggling with blocking shell cmd when using System.Process
Brandon Allbery
allbery.b at gmail.com
Tue Mar 20 23:15:20 CET 2012
On Tue, Mar 20, 2012 at 17:51, Rouan van Dalen <rvdalen at yahoo.co.uk> wrote:
> If I try to su the runShell function with the following command, it simply
> blocks forever:
>
> git --no-pager blame <your git file here>
>
> but if I do:
>
> git status
>
> The runShell function works as expected. Can someone shed some light on
> why the 'git blame' command blocks? Interrestingly enough, if I
>
You're trying to run the command and then collect all the output afterward;
this requires the OS to buffer potentially very large amounts of data,
whereas most OSes cache only a very small amount over a pipe. You will
need to read the data as the command runs to avoid blocking, then close the
process once you have read EOF.
--
brandon s allbery allbery.b at gmail.com
wandering unix systems administrator (available) (412) 475-9364 vm/sms
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