#! /usr/bin/env python3.2

from subprocess import Popen, PIPE, STDOUT

open('file.txt', 'w').write("a")

_in = open('/dev/null', "wb")
_err = _in
#_err = open('/dev/null', "wb")

Popen(['cat', 'file.txt'], stdout = PIPE, stdin = _in, stderr = _err)

print('OK')