Create a pipeline of (bash) commands using subprocess and trollius (or asyncio)

simple-subprocess-pipeline.py

import trollius
from trollius import From
# from trollius import Return
from trollius import gather
from trollius import create_subprocess_shell


# create dummy bash programs
def bash_program(name, sleep, code):
    with open(name, 'w') as f:
        f.write("""sleep %s
        echo %s finished
        exit %s""" % (sleep, name, code))
    return 'sh ' + name


flash = bash_program("flash.sh", 3, 10)
rapide = bash_program("rapide.sh", 5, 11)
lent = bash_program("lent.sh", 10, 21)


@trollius.coroutine
def join(*processus):
    """Wait that all `processus` are finished before returning"""
    # https://docs.python.org/3/library/asyncio-task.html#asyncio.gather
    yield From(gather(*map(lambda x: x.wait(), processus)))


@trollius.coroutine
def command_tree():
    # Le global est necessaire dans le cadre de l'exemple "self-contained"
    global flash, rapide, lent
    # Utilisation de `create_subprocess_shell` api haut niveau de trollius
    # d'autre façon d'interagir avec le processus existent, avec stdout
    # stdin ou a travers des signaux
    #
    #    https://docs.python.org/3/library/asyncio-subprocess.html#asyncio.create_subprocess_shell
    #
    # Voir aussi:
    #
    #    https://docs.python.org/3/library/asyncio-subprocess.html#subprocess-examples
    #
    # Et:
    #
    #    https://docs.python.org/3/library/asyncio-subprocess.html#process
    c = yield From(create_subprocess_shell(lent))
    b = yield From(create_subprocess_shell(rapide))
    a = yield From(create_subprocess_shell(flash))

    # wait for all programs to be finished
    yield join(a, b, c)

    print 'voila le mot de passe:', a.returncode + b.returncode + c.returncode

loop = trollius.get_event_loop()
loop.run_until_complete(command_tree())

maybe replace L51 yield with yield from