#! /usr/bin/python
import os
import sys

pipein, pipeout = os.pipe()

if os.fork() == 0:
    # child
    os.close(pipein)
    os.dup2(pipeout, 1)
    os.close(pipeout)
    os.execv("/usr/bin/seq", ["seq", "0", "10000"])
else:
    # parent
    os.close(pipeout)
    os.dup2(pipein, 0)
    os.close(pipein)
    os.execv("/bin/grep", ["grep", "235"])