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1. apt install libffi-dev

2. install pyenv based on https://www.tecmint.com/pyenv-install-and-manage-multiple-python-versions-in-linux/, but..

3. .. but instead of pyenv-virtualenv install pyenv-virtualenvwrapper (which can be standalone library or pyenv plugin, here the 2nd option):

   pyenv install 3.9.0

   git clone https://github.com/pyenv/pyenv-virtualenvwrapper.git $(pyenv root)/plugins/pyenv-virtualenvwrapper

   into ~/.bashrc add: export $VIRTUALENVWRAPPER_PYTHON="/usr/bin/python3"

   source ~/.bashrc

   pyenv virtualenvwrapper

1. apt install libffi-dev

2. install pyenv based on https://www.tecmint.com/pyenv-install-and-manage-multiple-python-versions-in-linux/, but..

3. .. but instead of pyenv-virtualenv install pyenv-virtualenvwrapper (which can be standalone library or pyenv plugin, here the 2nd option):

   $ pyenv install 3.9.0 $ git clone https://github.com/pyenv/pyenv-virtualenvwrapper.git $(pyenv root)/plugins/pyenv-virtualenvwrapper # inside ~/.bashrc add: # export $VIRTUALENVWRAPPER_PYTHON="/usr/bin/python3" $ source ~/.bashrc $ pyenv virtualenvwrapper 

• pyenv - manages different python versions,
• all others - create virtual environment (which has isolated python version and installed "requirements"),

pipenv want combine all, in addition to previous it installs "requirements" (into the active virtual environment or create its own if none is active)

So maybe you will be happy with pipenv only.

But I use: pyenv + pyenv-virtualenvwrapper, + pipenv (pipenv for installing requirements only).

In Debian:

1. apt install libffi-dev

2. install pyenv based on https://www.tecmint.com/pyenv-install-and-manage-multiple-python-versions-in-linux/, but..

3. .. but instead of pyenv-virtualenv install pyenv-virtualenvwrapper (which can be standalone library or pyenv plugin, here the 2nd option):

   pyenv install 3.9.0

   git clone https://github.com/pyenv/pyenv-virtualenvwrapper.git $(pyenv root)/plugins/pyenv-virtualenvwrapper

   into ~/.bashrc add: export $VIRTUALENVWRAPPER_PYTHON="/usr/bin/python3"

   source ~/.bashrc

   pyenv virtualenvwrapper

Then create virtual environments for your projects (workingdir must exist):

pyenv local 3.9.0 # to prevent 'interpreter not found' in mkvirtualenv python -m pip install --upgrade pip setuptools wheel mkvirtualenv <venvname> -p python3.9 -a <workingdir> 

and switch between projects:

workon <venvname> python -m pip install --upgrade pip setuptools wheel pipenv 

Inside a project I have the file requirements.txt, without fixing the versions inside (if some version limitation is not neccessary). You have 2 possible tools to install them into the current virtual environment: pip-tools or pipenv. Lets say you will use pipenv:

pipenv install -r requirements.txt 

this will create Pipfile and Pipfile.lock files, fixed versions are in the 2nd one. If you want reinstall somewhere exactly same versions then (Pipfile.lock must be present):

pipenv install 

Remember that Pipfile.lock is related to some Python version and need to be recreated if you use a different one.

As you see I write requirements.txt. This has some problems: You must remove a removed package from Pipfile too. So writing Pipfile directly is probably better.

So you can see I use pipenv very poorly. Maybe if you will use it well, it can replace everything?

• pyenv - manages different python versions,
• all others - create virtual environment (which has isolated python version and installed "requirements"),

pipenv want combine all, in addition to previous it installs "requirements" (into the active virtual environment or create its own if none is active)

So maybe you will be happy with pipenv only.

But I use: pyenv + pyenv-virtualenvwrapper, + pipenv (pipenv for installing requirements only).

In Debian:

1. apt install libffi-dev

2. install pyenv based on https://www.tecmint.com/pyenv-install-and-manage-multiple-python-versions-in-linux/, but..

3. .. but instead of pyenv-virtualenv install pyenv-virtualenvwrapper (which can be standalone library or pyenv plugin, here the 2nd option):

   pyenv install 3.9.0

   git clone https://github.com/pyenv/pyenv-virtualenvwrapper.git $(pyenv root)/plugins/pyenv-virtualenvwrapper

   into ~/.bashrc add: export $VIRTUALENVWRAPPER_PYTHON="/usr/bin/python3"

   source ~/.bashrc

   pyenv virtualenvwrapper

Then create virtual environments for your projects (workingdir must exist):

pyenv local 3.9.0 # to prevent 'interpreter not found' in mkvirtualenv python -m pip install --upgrade pip setuptools wheel mkvirtualenv <venvname> -p python3.9 -a <workingdir> 

and switch between projects:

workon <venvname> python -m pip install --upgrade pip setuptools wheel pipenv 

Inside a project I have the file requirements.txt, without fixing the versions inside (if some version limitation is not neccessary). You have 2 possible tools to install them into the current virtual environment: pip-tools or pipenv. Lets say you will use pipenv:

pipenv install -r requirements.txt 

this will create Pipfile and Pipfile.lock files, fixed versions are in the 2nd one. If you want reinstall somewhere exactly same versions then (Pipfile.lock must be present):

pipenv install 

Remember that Pipfile.lock is related to some Python version and need to be recreated if you use a different one.

As you see I write requirements.txt. This has some problems: You must remove a removed package from Pipfile too. So writing Pipfile directly is probably better.

So you can see I use pipenv very poorly. Maybe if you will use it well, it can replace everything?

EDIT 2021.01: I have changed my stack to: pyenv + pyenv-virtualenvwrapper + poetry. Ie. I use no apt or pip installation of virtualenv or virtualenvwrapper, and instead I install pyenv's plugin pyenv-virtualenvwrapper. This is easier way.

Poetry is great for me:

poetry add <package> # install single package poetry remove <package> poetry install # if you remove poetry.lock poetry will re-calculate versions 

• pyenv - manages different python versions,
• all others - create virtual environment (which has isolated python version and installed "requirements"),

pipenv want combine all, in addition to previous it installs "requirements" (into the active virtual environment or create its own if none is active)

So maybe you will be happy with pipenv only.

But I use: pyenv + pyenv-virtualenvwrapper, + pipenv for installing requirements only.

In Debian:

1. apt install libffi-dev python3-virtualenv

2. install pyenv based on https://www.tecmint.com/pyenv-install-and-manage-multiple-python-versions-in-linux/, but..

3. ..instead of pyenv-virtualenv install pyenv-virtualenvwrapper:

   pyenv global system 3.9.0 # python stays 2.7.x + python3 is 3.9.0

   python3.9 -m pip install --upgrade pip setuptools wheel

   git clone https://github.com/pyenv/pyenv-virtualenvwrapper.git $(pyenv root)/plugins/pyenv-virtualenvwrapper

   pyenv virtualenvwrapper # maybe you must restart shell before: source ~/.bashrc

Then create virtual environments for your projects (workingdir must exist):

mkvirtualenv <venvname> -p python3.9 -a <workingdir> 

and switch between projects:

workon <venvname> 

Inside a project I have the file requirements.txt, without fixing the versions inside (if some version limitation is not neccessary). You have 2 possible tools to install them into the current virtual environment: pip-tools or pipenv. Lets say you will use pipenv:

pipenv install -r requirements.txt 

this will create Pipfile and Pipfile.lock files, fixed versions are in the 2nd one. If you want reinstall somewhere exactly same versions then (Pipfile.lock must be present):

pipenv install 

Remember that Pipfile.lock is related to some Python version and need to be recreated if you use a different one.

As you see I write requirements.txt. This has some problems: You must remove a removed package from Pipfile too. So writing Pipfile directly is probably better.

So you can see I use pipenv very poorly. Maybe if you will use it well, it can replace everything?

• pyenv - manages different python versions,
• all others - create virtual environment (which has isolated python version and installed "requirements"),

pipenv want combine all, in addition to previous it installs "requirements" (into the active virtual environment or create its own if none is active)

So maybe you will be happy with pipenv only.

But I use: pyenv + pyenv-virtualenvwrapper, + pipenv (pipenv for installing requirements only).

In Debian:

1. apt install libffi-dev

2. install pyenv based on https://www.tecmint.com/pyenv-install-and-manage-multiple-python-versions-in-linux/, but..

3. .. but instead of pyenv-virtualenv install pyenv-virtualenvwrapper (which can be standalone library or pyenv plugin, here the 2nd option):

   pyenv install 3.9.0

   git clone https://github.com/pyenv/pyenv-virtualenvwrapper.git $(pyenv root)/plugins/pyenv-virtualenvwrapper

   into ~/.bashrc add: export $VIRTUALENVWRAPPER_PYTHON="/usr/bin/python3"

   source ~/.bashrc

   pyenv virtualenvwrapper

Then create virtual environments for your projects (workingdir must exist):

pyenv local 3.9.0 # to prevent 'interpreter not found' in mkvirtualenv python -m pip install --upgrade pip setuptools wheel mkvirtualenv <venvname> -p python3.9 -a <workingdir> 

and switch between projects:

workon <venvname> python -m pip install --upgrade pip setuptools wheel pipenv 

Inside a project I have the file requirements.txt, without fixing the versions inside (if some version limitation is not neccessary). You have 2 possible tools to install them into the current virtual environment: pip-tools or pipenv. Lets say you will use pipenv:

pipenv install -r requirements.txt 

this will create Pipfile and Pipfile.lock files, fixed versions are in the 2nd one. If you want reinstall somewhere exactly same versions then (Pipfile.lock must be present):

pipenv install 

Remember that Pipfile.lock is related to some Python version and need to be recreated if you use a different one.

As you see I write requirements.txt. This has some problems: You must remove a removed package from Pipfile too. So writing Pipfile directly is probably better.

So you can see I use pipenv very poorly. Maybe if you will use it well, it can replace everything?