Invoking modules with python -m

Mon, 06 Jul 2026 00:00:00 +0000

Python has the -m flag, which locates a module and runs it as a script. And the standard library is full of modules that turn into command line utilities ready to use, with nothing to install.

Serve the current folder over HTTP:

python -m http.server

Format (and validate) a JSON:

echo '{"name": "cassio", "language": "python"}' | python -m json.tool

See the calendar for the year in your terminal:

python -m calendar 2026

You have probably already used the flag without noticing, in commands like python -m venv .venv or python -m pip install. It is the same mechanism: -m locates the module on the import path and executes it as the main program, with __name__ set to "__main__" (when the target is a package, what runs is its __main__.py).

Cli on cassiobotaro

Invoking modules with python -m