main entry

def main():
    '''main entry'''

    cli = docker.from_env()

    try:
        opts, args = getopt.gnu_getopt(sys.argv[1:], "pcv", ["pretty", "compose"])
    except getopt.GetoptError as _:
        print("Usage: docker-parse [--pretty|-p|--compose|-c] [containers]")
        sys.exit(2)

    if len(args) == 0:
        containers = cli.containers.list(all=True)
    else:
        containers = map(lambda nm: cli.containers.get(nm), args)

    as_compose = False
    pretty = False
    for opt, _ in opts:
        if opt == '-v':
            print(__version__)
            sys.exit()
        elif opt == '-p' or opt == '--pretty':
            pretty = True
            break
        elif opt == '-c' or opt == '--compose':
            as_compose = True
            break

    for container in containers:
	info = container.attrs

        # diff with image info to reduce information
        image_info = cli.images.get(info['Config']['Image']).attrs

        if as_compose:
            output_compose(info, image_info)
        else:
            output_command(info, image_info, pretty)