Quick Guide to install Pyenv **tool for managing multiple Python versions**

pyenv_installation.md

Pyenv Installation

Ubuntu Installation

1. Install build dependencies sudo apt-get install -y make build-essential libssl-dev zlib1g-dev \ libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev \ libncursesw5-dev xz-utils tk-dev libffi-dev liblzma-dev python-openssl
2. Install pyenv curl https://pyenv.run | bash
3. Add following lines to ~/.bashrc

export PYENV_ROOT="$HOME/.pyenv"
export PATH="/home/pi/.pyenv/bin:$PATH"
eval "$(pyenv init -)"
eval "$(pyenv virtualenv-init -)"

4. If you are combining pyenv and pipenv, then set the environment variable PIPENV_PYTHON to $PYENV_ROOT/shims/python. This will make Pipenv use pyenv’s active Python version to create virtual environments by default.
5. Add PIPENV_PYTHON="$PYENV_ROOT/shims/python" to ~/.bashrc. And reload your shell exec "$SHELL"
6. Check available python versions pyenv install --list | grep " 3\.[678]". To see all pyenv install --list
7. Install the version you need, for instance pyenv install -v 3.7.2
8. To see where the python versions are installed enter ls ~/.pyenv/versions/
9. Remove, if you need, by entering rm -rf ~/.pyenv/versions/3.7.2 or pyenv uninstall 3.7.2
10. Check what versions of Python you have available, pyenv versions (* indicates the system Python version)

* system (set by /home/pi/.pyenv/version)
  3.7.2

11. To confirm use which python
12. To use version 3.7.2, then you can use the global command pyenv global 3.7.2
13. Check python version now pyenv version

 system 
  3.7.2 (set by /home/pi/.pyenv/version)

14. To go back to the system version of Python enter pyenv global system and check version to confirm.

MacOS Installation

1. Install build dependencies brew install openssl readline sqlite3 xz zlib
2. Install pyenv curl https://pyenv.run | bash
3. Add following lines to ~/.bashrc

export PYENV_ROOT="$HOME/.pyenv"
export PATH="/home/pi/.pyenv/bin:$PATH"
eval "$(pyenv init -)"
eval "$(pyenv virtualenv-init -)"

4. If you are combining pyenv and pipenv, then set the environment variable PIPENV_PYTHON to $PYENV_ROOT/shims/python. This will make Pipenv use pyenv’s active Python version to create virtual environments by default.
5. Add PIPENV_PYTHON="$PYENV_ROOT/shims/python" to ~/.bashrc. And reload your shell exec "$SHELL"
6. Check available python versions pyenv install --list | grep " 3\.[678]". To see all pyenv install --list
7. Install the version you need, for instance pyenv install -v 3.7.2
8. To see where the python versions are installed enter ls ~/.pyenv/versions/
9. Remove, if you need, by entering rm -rf ~/.pyenv/versions/3.7.2 or pyenv uninstall 3.7.2
10. Check what versions of Python you have available, pyenv versions (* indicates the system Python version)

* system (set by /home/pi/.pyenv/version)
  3.7.2

11. To confirm use which python
12. To use version 3.7.2, then you can use the global command pyenv global 3.7.2
13. Check python version now pyenv version

 system 
  3.7.2 (set by /home/pi/.pyenv/version)

14. To go back to the system version of Python enter pyenv global system and check version to confirm.

Pro Tip To check the version of Python installed is working properly is to run the built-in test suite.

$ pyenv global 3.8-dev
$ python -m test
----->will verify your installation<---------

For further detail info go to Intro-to-pyenv