Welcome to Commis

Commis is a library to create command line utilities like git or django-admin where there is a single command that implements many subcommands. Internally, Commis uses the argparse module to create subparsers and parse command line options. However, much like the Django management utility, it exposes an API that allows you to write command classes and create very simple console programs.

Getting Started

To install the Commis library, the simplest thing to do is use pip as follows:

$ pip install commis

Alternatively, you can download the latest (development) version or clone directly from Github and install it using the setup.py script:

$ git clone https://github.com/bbengfort/commis.git
$ cd commis
$ python setup.py install

Writing Commands

Basically the way you create commands is to subclass the Command class, define its name, help, and args attributes, then implement a handle method. This more or less looks as follows:

class GreetingCommand(Command):

    name    = "greeting"
    help    = "an example command, delivers a greeting"

    args    = {
        # Language selection option
        ('-l', '--lang'): {
            'type': str,
            'default': 'english',
            'metavar': 'LANG',
            'choices': ['english', 'french', 'spanish'],
            'help': 'the language of the greeting',

        # List of one or more name arguments
        'name': {
            'nargs': "+",
            'type': str,
            'help': 'the name to greet you by'

    def handle(self, args):
        Greet each person by name.
        salutation = {
            'french': 'Bonjour',
            'spanish': 'Hola',
            'english': 'Hello',

        output = []
        for name in args.name:
            output.append("{} {}!".format(salutation, name))
        return "\n".join(output)

The args is a Python dictionary of keyword arguments to be passed to argparse.add_argument and uses the same syntax. See the add_argument method for more details.

The handle method should accept args as its only argument, and should return a string to be printed to the command line.

Writing a Console Program

Once you have your commands, you need to create and define a console utility to execute them. Simply subclass ConsoleProgram with your definition as follows:

DESCRIPTION = "Inspects the mimetype distribution of a directory."
EPILOG      = "Created for scientific purposes and not diagnostic ones."

class ExampleUtility(ConsoleProgram):

    description = DESCRIPTION
    epilog      = EPILOG
    version     = commis.__version__

    def load(klass, commands=COMMANDS):
        utility = klass()
        for command in commands:
        return utility

The ConsoleProgram has a register method which allows you to register various commands. You can do this at run time, creating dynamic utilities with different commands, or you can explore a directory and load all commands from it. Here I just simply add a simple load static method to load the commands and instantiate the utility. Using the utility is then as simple as creating a script as follows:

from example import ExampleUtility

if __name__ == '__main__':
    utility = ExampleUtility.load()

For more on writing console utilities and programs, check out the tutorial which follows.