pipeline() helper for chaining subprocess.Popen() instances conveniently

pipeline.py

import subprocess


def pipeline(*commands):
    """Chain several commands into a pipeline.

    E.g. to get the equivalent of

        $ zcat foo | grep bar | less

    do

        pipeline(["zcat", "foo"], ["grep", "bar"], ["less"])

    """
    if len(commands) < 2:
        raise TypeError('at least two commands needed to form a pipeline')
    p = subprocess.Popen(commands[0], stdout=subprocess.PIPE)
    for cmd in commands[1:-1]:
        p = subprocess.Popen(cmd, stdin=p.stdout, stdout=subprocess.PIPE)
    p = subprocess.Popen(commands[-1], stdin=p.stdout)
    p.wait()

See also https://github.com/ProgrammersOfVilnius/pov-server-page/blob/22177c51e55af393fb06c32b83524ea6000b7b25/update_server_page.py#L146