os.pipes() - need help!

[Sven Drescher]

Hi!

I'm really hopeless. I tried for a week to use pipes, but nothing happend.
The information I found on the homepages and in Deja-News aren't enough for
me.
I found the following example:

#!/usr/local/bin/python

import os
import sys

#pipes definieren

pipe1 = os.pipe() # parent stdin, child stdout
pipe2 = os.pipe() # child stdin, parent stdout

pid=os.fork()
if pid:
    os.close(pipe1[1]) # child stdout - close
    os.close(pipe2[0]) # child stdin - close
    os.dup2(pipe1[0], 0) # sys.stdin = parent stdin
    os.dup2(pipe2[1], 1) # sys.stdout = parent stdout

else:
    os.close(pipe1[0]) # parent stdin - close
    os.close(pipe2[1]) # parent stdout - close
    os.dup2(pipe2[0], 0) # sys.stdin = child stdin
    os.dup2(pipe1[1], 1) # sys.stdout = child.stdout

    os.execv("/usr/openwin/bin/xterm", ["xterm"])

    sys.stdout.write("ls\n")
    sys.stdout.flush()

So, now I don't know why nothing happens. I tried various combinations and
also print and others - no result!!!

Thanks for help!

Sven