Pipe a String into a Program's Input in Python

stringpiper.py

#!/usr/bin/env python2.7
# -*- coding: utf-8 -*-

import argparse
import subprocess

from StringIO import StringIO


def __main__():
    parser = argparse.ArgumentParser(prog="piper", description="Pipes output of two programs together.")
    parser.parse_args()
    
    sio = StringIO("hello world\n")

    p = subprocess.Popen(['cat'], stdin=subprocess.PIPE, stdout=subprocess.PIPE)
    
    # await results of the pipe
    output = p.communicate(input=sio.read())[0]
    
    # outputs:
    # rc:0, output:hello world
    print("rc:{returncode}, output:{output}".format(returncode=p.returncode, output=output.strip()))

if __name__ == "__main__":
    __main__()