Re: [Haskell-cafe] Re: Running a "sub-process" which dies with the main program

19 Jun 2009

      2009/6/19 Aycan iRiCAN :
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Cum, 2009-06-19 tarihinde 12:42 +0200 saatinde, Deniz Dogan yazdı:
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2009/6/19 Aycan iRiCAN :
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Cum, 2009-06-19 tarihinde 11:58 +0200 saatinde, Deniz Dogan yazdı:
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2009/6/18 Deniz Dogan :
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Hi
I couldn't come up with a better subject than this one, so anyways...
I have a small program which spawns a subprocess. However, when I hit
C-c, the subprocess won't die, instead it will just keep running until
it's done or until I kill it. I've looked around in System.Process for
something suitable for my needs, but I can't seem to find it. Any
ideas?
With a tip from a person outside of the mailing list I found
System.Process.system, which essentially does exactly what I was
asking for.
Hey I'm already subscribed :) You can read from "sout" and "serr" with
below example. Hope that it helps.
module Main where
import System.Process  -- using process-1.0.1.1
main = do
 (_, sout, serr, p) <- createProcess (proc "sleep" ["10"])
                       { std_out = CreatePipe
                       , std_err = CreatePipe }
 r <- waitForProcess p
 return ()
Thanks!
But this was the approach I used before I went to
System.Process.system and it did not work on my Linux machine.
Give it a try. Try to send CTRL-C and look if "sleep 10" (which is a
subprocess) process terminates.
aycan@aycan:~/haskell$ time ./deniz2 && ps -ef | grep sleep
^C
real    0m0.707s
user    0m0.001s
sys     0m0.004s
  aycan 13098  4430   0 13:50:23 pts/7       0:00 grep sleep
It terminates with ghc 6.10.3 on OpenSolaris.
This is copied verbatim from my terminal. I used the exact some code
that you gave me.

% time ./test && ps -ef | grep sleep
^C
real	0m10.005s
user	0m0.003s
sys	0m0.003s
deniz    14095 14047  0 13:05 pts/1    00:00:00 grep sleep

What's strange though is that when I hit C-c *twice*, I get this behavior:

time ./test && ps -ef | grep sleep
^C^C

real	0m0.915s
user	0m0.003s
sys	0m0.000s

This is with GHC 6.10.3 on Arch Linux i686.

--
Deniz Dogan