Correction to linux install instructions

I just started an installation of Octoprint on x86 debian (the machine runs constantly and is near the printer so I didn't want to dedicate a Pi to it), following the instructions at Setting up OctoPrint on a Raspberry Pi running Raspberry Pi OS (Debian)

However, I got an error at 'pip install pip --upgrade'
Traceback (most recent call last):
File "/usr/local/bin/pip", line 5, in
from pip._internal.cli.main import main
File "/home/adrian/.local/lib/python3.9/site-packages/pip/init.py", line 6
def main(args: Optional[List[str]] = None) -> int:
^
SyntaxError: invalid syntax

Initially very frustrating as this is all too often my experience of python : something has changed and there is an incompatibility between what's needed and what's installed. Usually I enter a world of hurt resulting in permanent damage to other bits of the system. I know venv is intended to stop this but for some bizarre reasons it's left to users to debug rather than being part of the installation script.

However, in this case it was an easy fix, for which I was very glad - the first 'pip' in that and the following commands needs to be the python3 one. On my debian system, which has both 2.7 and 3.9 installed, that needs to be invoked specifically as pip3

So

pip3 install pip --upgrade
pip3 install octoprint

After installing, it still fails because Octoprint isn't in Octoprint/venv/bin but it is on the path. So it runs just as

octoprint serve

A venv is definitely recommended, and it's part of the installation guide. If you follow the guide exactly, and don't try installing OctoPrint at a system level then you won't run into the problem you did with the system pip being Python 2, which is the same for everyone running RPi OS/Debian. It includes creating and activating the virtual environment here:

Yes, I realise a venv is needed, and I appreciate the mention of it in the instructions.

However, it appears almost impossible to run python scripts without one. I'm suggesting that python should do it itself rather than leaving it to the end user.

I followed the instructions as written, performing the pip steps after sourcing the venv script. But got the error described unless I used pip3.