Quick install pyenv and Python

Tested only on Ubuntu 18.04 and KDE Neon User Edition (based on Ubuntu 18.04).

will probably work on other newer versions, with no changes, or with few changes in non-python dependencies (apt-get packages)

NOTE: Don't create a .sh file and run it all at once. It will not work. Copy, paste, and execute each command below manually. :-)

# DO NOT RUN THIS AS A ROOT USER
# Enter your password when prompted.
# your user must be allowed to run "sudo"
sudo bash -c "echo -e 'Starting...\n'"
sudo apt-get update;
# install most common python interpreter itself compile dependencies
sudo apt-get install aria2 build-essential curl git libbz2-dev libffi-dev liblzma-dev libncurses5-dev libncursesw5-dev libreadline-dev libsqlite3-dev libssl-dev llvm make tk-dev wget xz-utils zlib1g-dev --yes;
# install pyenv
curl -L https://github.com/pyenv/pyenv-installer/raw/master/bin/pyenv-installer | bash
# install a virtualenvwrapper plugin to pyenv
git clone https://github.com/pyenv/pyenv-virtualenvwrapper.git $HOME/.pyenv/plugins/pyenv-virtualenvwrapper
# add pyenv required configurations 
if ! egrep -q "^[#]{4}[[:space:]]pyenv[[:space:]]config$" "${HOME}/.bashrc" ; then echo -e "\n\nsetup pyenv configuration:\nThe following content was inserted at the end of the ${HOME}/.bashrc file\n"; echo -e '\n#### pyenv config\nif [ -f "$HOME/.pyenv/bin/pyenv" ] && ! type -P pyenv &>/dev/null ; then\n  export PYTHON_CONFIGURE_OPTS="--enable-shared"\n  export CFLAGS="-O2"\n  export PYTHON_BUILD_ARIA2_OPTS="-x 10 -k 1M"\n  export PATH="$HOME/.pyenv/bin:$PATH"\n  eval "$(pyenv init -)"\n  eval "$(pyenv virtualenv-init -)"\n  if [[ ! "$(pyenv which python)" == "/usr/bin/python" ]] ; then \n    pyenv virtualenvwrapper_lazy;\n  fi\nfi\n#### pyenv config end' | tee --append "${HOME}/.bashrc"; source "$HOME/.bashrc"; else  echo -e "\n\npyenv configuration already installed in $HOME/.bashrc"; fi
# reload .bashrc to run pyenv configurations
source $HOME/.bashrc
# download and compile python 3.8.2
pyenv install 3.8.2
# download and compile python 2.7.17
pyenv install 2.7.17
# set "python", "python3", "python3.8" to point python3.8.2, and "python2" and "python2.7" to point python2.7.17
pyenv global 3.8.2 2.7.17
# reload .bashrc to run pyenv configurations again
source $HOME/.bashrc
python3 -m pip install pip setuptools wheel virtualenv virtualenvwrapper -U
python2 -m pip install pip setuptools wheel virtualenv virtualenvwrapper -U

CoutinhoElias/installing_pyenv_on_ubuntu_based_distros.md