Install pyenv on Ubuntu

install_pyenv.sh

#!/bin/bash

sudo apt-get install git python-pip make build-essential libssl-dev zlib1g-dev libbz2-dev libreadline-dev libsqlite3-dev curl
sudo pip install virtualenvwrapper

git clone https://github.com/yyuu/pyenv.git ~/.pyenv
git clone https://github.com/yyuu/pyenv-virtualenvwrapper.git ~/.pyenv/plugins/pyenv-virtualenvwrapper

echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.bashrc
echo 'export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.bashrc
echo 'eval "$(pyenv init -)"' >> ~/.bashrc
echo 'pyenv virtualenvwrapper' >> ~/.bashrc

exec $SHELL

For Ubuntu 21.10, additional line:

sudo apt-get install python-is-python3