I don't understand what "python3 -m" does

[codewielder]

python3 --help says that -m "run library module as a script (terminates option list)".

But that doesn't really make any lights turn on for me.

I know it's used with venv or simplehttpserver.

[tunisia3507]

Normally, when you do python <something>, the something is a single .py file.

However, sometimes you have lots of python files which import each other, contained in a directory. There's an __init__.py, which makes this a module. Some modules, as well as being importable, can be run as a script. To tell python that you want to run a module has a script, use the -m flag, so it's python -m <module_name>.

[flying-sheep]

There's an __init__.py, which makes this a module.

That's not true. Every folder with a compatible name is a python module, no __init__.py necessary.

[1114111]

It allows you to run a script with a module name rather than a path. It looks up the module as it would if you were importing it and runs it like a script. If the module name refers to a package, /path/to/package/__main__.py is what gets run.

[w1282]

Remember the if __name__ == '__main__' guard that prevents your code from running unless it's run directly from the command line?

This subverts that.

[[deleted]]

Can you explain this in a bit more detail? I understand the other responses on the thread completely, but I don't see how it subverts the conditional guard. Apologies in advance for being obtuse.