Python 3.12.1, Windows 11: shebang line #!/usr/bin/env python3 doesn't work any more

[Mats Wichmann]

On 1/1/24 04:02, Sibylle Koczian via Python-list wrote:
> Am 30.12.2023 um 04:04 schrieb Mike Dewhirst via Python-list:
>>
>> I had assumed the OP had installed Python from the Microsoft shop and 
>> that's where py.exe must have come from.
>>
> 
> In fact I didn't say in my post that I always get Python from 
> python.org. When I started to use the language there was no Python from 
> any Microsoft shop (I'm not sure there was a Microsoft shop, it was in 
> the last millenium, Python 1.5 or 1.6). So I tend to forget that 
> possible download source.
> 
> But in all this thread I didn't see a single explanation for my current 
> situation: one and the same shebang line works on Windows 10 / Python 
> 3.11 and doesn't work on Windows 11 / Python 3.12. I suspect Windows, 
> because a change in the way Python 3.12 uses shebang lines should be 
> visible in the documentation.

The shebang support in the Python Launcher is documented here:

https://docs.python.org/3/using/windows.html#shebang-lines

That says the line you list originally:

 > My shebang line is usually "#!/usr/bin/env python3"

means look for python3 in PATH.  Do you have one? If you don't have one, 
you'll get one you don't want: the stupid Microsoft shim that, which if 
run interactively, encourages you to install from the Microsoft store. 
You should be able to disable this.

File suffix associations are a different thing - they give me no end of 
headaches on Windows. They start out bound to the shim, and should 
rebind to the launcher when you install, but then things can steal it. 
If you install Visual Studio Code with Python extensions, then it takes 
over the running of .py files - if you click in the explorer, you'll get 
it open in the editor, not run.  I've argued about this, to no avail 
(plays havoc with my testsuite, which in some places tries to execute 
Python scripts as a cli command).

And then I've got this:

C:\Users\mats\SOMEWHERE>py -0
  -V:3.13          Python 3.13 (64-bit)
  -V:3.12 *        Python 3.12 (64-bit)
  -V:3.11          Python 3.11 (64-bit)
  -V:3.10          Python 3.10 (64-bit)
  -V:3.9           Python 3.9 (64-bit)
  -V:3.8           Python 3.8 (64-bit)
  -V:3.7           Python 3.7 (64-bit)
  -V:3.6           Python 3.6 (64-bit)

# Okay, it knows about lots of Python versions, and shows a default of 3.12

C:\Users\mats\SOMEWHERE>py
Python 3.12.1 (tags/v3.12.1:2305ca5, Dec  7 2023, 22:03:25) [MSC v.1937 
64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
 >>> ^Z

# Great, that works just as expected

C:\Users\mats\SOMEWHERE>py test.py
Python was not found; run without arguments to install from the 
Microsoft Store, or disable this shortcut from Settings > Manage App 
Execution Aliases.

# wait, what? if "py" worked, why doesn't "py test.py"?