Document why global pip install is used

[clach04]

Explain why, and discourage anyone from attempting to use virtualenv/venv.

Current scripts expect global install, flash will fail if venv used.

[rpavlik]

I was wondering this too, I'm often hesitant to install modules system-wide. Could the script instead set up a venv and use it? Python 3 comes with venv built-in...

[quentinsf]

Recent versions of Python 3 will try to stop you doing global pip installs and warn you that this is an 'externally managed environment'.
The easiest way to bypass this and allow the install_prereq.sh script to complete is to remove the files which mark it as such:

sudo rm /usr/lib/python3.*/EXTERNALLY-MANAGED

[clach04]

Recent versions of Python 3 will try to stop you doing global pip installs and warn you that this is an 'externally managed environment'. The easiest way to bypass this and allow the install_prereq.sh script to complete is to remove the files which mark it as such:

sudo rm /usr/lib/python3.*/EXTERNALLY-MANAGED

Interesting. I'm not in a position to experiment but if I end up doing this again I will see what this does (I'm obviously going to use caution with both sudo and rm with wild cards! 😉 )

Note to self, alternatively use Docker :-)

[rpavlik]

There's also a flag called "--break-system-packages" to just ignore those EXTERNALLY-MANAGED files.