Re: [Haskell-cafe] System.Posix, forked processes and psuedo terminals on Linux

21 Aug 2010


      Quoth Erik de Castro Lopo ,
...
...
The code below *almost* works. Its currently printing out:
parent : Forked child was here!
    parent : Message from parent.
    Read 21 bytes
while I think it should print:
parent : Forked child was here!
    parent : Read 21 bytes
Any clues on why 'Message from parent.' is also ending up on
stdout? This is ghc-6.12.1 on Debian Linux.
My guess is that the default tty attributes include ECHO.  So the
data you write to the master fd is echoed back, as though by the
fork process but actually by the terminal driver.  You can turn
ECHO off.

	Donn Cave, donn@avvanta.com