How to install and run virtualenv on MacOS correctly

Question

Hi I'm a beginner of python, I don't remember when and how I installed python3.8 on my Macbook air, only knew the installed path:

% which python
/usr/bin/python
% which python3
/usr/local/bin/python3

The pip command cannot not be found but pip3 is ok. Today I want to install virtaulenv:

% sudo -H pip3 install virtualenv
WARNING: Ignoring invalid distribution - (/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages)
Successfully installed virtualenv-20.6.0

I can use "pip3 show virtualenv" to know the info:

% pip3 show virtualenv
Name: virtualenv
Version: 20.6.0
Summary: Virtual Python Environment builder
Home-page: https://virtualenv.pypa.io/
Author: Bernat Gabor
Author-email: gaborjbernat@gmail.com
License: MIT
Location: /Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages
Requires: six, platformdirs, backports.entry-points-selectable, distlib, filelock
Required-by:

But when I use "virtualenv" I got command not found message then I "pip3 uninstall" it. I searched for this and got a tip to use "easy_install" to install virtualenv. After installed I can execute the command, but got some error message:

% virtualenv                     
Traceback (most recent call last):
  File "/usr/local/bin/virtualenv", line 6, in <module>
    from pkg_resources import load_entry_point
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources/__init__.py", line 3241, in <module>
    @_call_aside
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources/__init__.py", line 3225, in _call_aside
    f(*args, **kwargs)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources/__init__.py", line 3254, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources/__init__.py", line 583, in _build_master
    ws.require(__requires__)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources/__init__.py", line 900, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources/__init__.py", line 786, in resolve
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'importlib-resources>=1.0' distribution was not found and is required by virtualenv

It seems doesn't work and I try the "sudo pip3 uninstall virtualenv" to uninstall it successfully, but it seems not really be removed:

% which virtualenv              
/usr/local/bin/virtualenv

I have no idea about this, could you help me? I just want to run virtualenv normally and create flask project ...

PS. I can "sudo pip3 install flask" and "pip3 show flask" but still cannot run flask cammand (command not found), what should I do?

Thanks a lot!

Answer 1

try being explicit in the version of python you are using and install using -m pip instead

python3 -m pip install virtualenv
python3 -m virtualenv venv # create a new venv in ./venv
source ./venv/bin/activate # activate your new venv

often times the pip/pip3 just isnt pointing at the same python version you think you are using... by using this technique you are sure to be using the correct python and pip