#!/usr/bin/env python

from subprocess import Popen, PIPE
import sys

input   = """input_data
zoological
aardvark
"""

outfile = file('outfile.txt','w')

# it blocks if create in left to right order, not sure why!

p2 = Popen(['sort'],                  stdin=PIPE, stdout=outfile)
p1 = Popen(['sed', 's/$/ hi there/'], stdin=PIPE, stdout=p2.stdin)

p2.stdin.close()  # I guess it was dup'd here and in p1

p1.communicate(input)

sys.exit(p2.returncode or p1.returncode)