On 12/22/2023 7:27 PM, Michael Torrie via Python-list wrote:
On 12/22/23 07:02, Thomas Passin via Python-list wrote:
On my Windows 10 machine, Python scripts run without a shebang line.
Perhaps Windows 11 has added the ability to use one, but then you would
need to use the actual location of your Python executable.
Yes if you associate .py or .pyw with python.exe (or pythonw.exe), then
things work as you describe. However it's no longer recommended to do
that.
Instead---and I think this is the default now when you install
python---you should associate both .py and .pyw files with the py
launcher (py.exe) and it will examine the shebang line of the script and
determine which version of python to run. As I said this should work
regardless of the path listed in the shebang. Note that the shebang is
meaningless to Windows itself, and Windows Explorer. It is only
meaningful to the py launcher. So it's customary to just use a
unix-style shebang in your python scripts. So either #!/usr/bin/python3
or #!/usr/bin/env python3 as you would in unix.
Using the py launcher as your Windows association with .py and.pyw files
you can have multiple versions of python installed and everything works
as it should, according to your shebang, just like on Unix.
I actually don't remember how to set up the association for Python
files. I just always type the "py" launcher anyway, as in
py -m pip instal ...
I think that the association with py.exe must only happen if you install
to Program Files. As I said in my previous post, Windows still sticks
with launching Python files with Python 3.9 even though I'm three
version beyond that. 3.9 is the only one I installed to Program Files.
In my experience one should always make sure to know what version of
Python is being used, at least if there is more than one version
installed on the computer. Even on Linux using a shebang line can be
tricky, because you are likely to get the system's version of Python,
and that often is not what you want. OTOH you don't want to go
symlinking python3 to some other version of python because then the OS
system may not work right. So either you have to specify the Python
version in the shebang, or just specify the right version on the command
line. In that case you might as well not have included the shebang line
at all.
I may be more sensitive to this issue because I run many different Linux
distros in VMs to check a few programs I support to make sure they can
run on Linux as well as Windows. What Linux, you ask? Well, who knows
what our users will use? So I'm always getting Python version
mix-and-match problems. The system will still be at Python 3.10 but I
need Python 3.11. The system uses Python 3.11 but we shouldn't (or
cannot) install our dependencies so we need a parallel install. Etc, etc.
It's just better not to make assumptions about which version of Python
will be running. Just specify it yourself when you can, and then you can
be sure.
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