replacement for popen

12 Apr 2005

      in the ghc-6.4 release the posix module is deprecated.
I'm looking for a replacement and tried the
System.Process functions. the following first try
does not work for large files. it blocks if the
file "long.file" does not fit into one os-buffer.
then cat blocks and therefor waitForProcess blocks

------------------------------------

module Main where

import IO
import System
import System.Process

main :: IO ()
main = do
       (inpH, outH, errH, pH) <- runInteractiveProcess "cat" ["long.file"] Nothing Nothing
       hClose inpH
       res  <- hGetContents outH
       errs <- hGetContents errH

       rc <- waitForProcess pH

       putStrLn ("rc: " ++ show rc)
       putStrLn ("stdout: " ++ res)
       putStrLn ("stderr: " ++ errs)
       exitWith rc

----------------------

the following version works fine, but it looks very much like a hack

---------------------

module Main where

import IO
import System
import System.Process

main :: IO ()
main = do
       (inpH, outH, errH, pH) <- runInteractiveProcess "cat" ["long.filel"] Nothing Nothing
       hClose inpH
       res  <- hGetContents outH
       errs <- hGetContents errH

       if (length $! res) == 0  -- hack !!!
	  then return ()
	  else return ()

       if (length $! errs) /= 0 -- hack !!!
	  then return ()
	  else return ()

       rc <- waitForProcess pH

       putStrLn ("rc: " ++ show rc)
       putStrLn ("stdout: " ++ res)
       putStrLn ("stderr: " ++ errs)
       exitWith rc

-------------------------------------

is there a simple replacement for the popen using the System.Process module?

uwe

-- 

University of Applied Sciences, Wedel, Germany
http://www.fh-wedel.de/~si/index.html
mail:uwe@fh-wedel.de
tel:++49-4103-8048-45

replacement for popen

Uwe Schmidt