How to install 'pyenv' Python version manager on Ubuntu 20.04

Overview:

pyenv - is a simple Python version manager tool, which allows you easily switch between multiple versions of Python. You can set local or global system-wide Python versions via the tool.

Installation:

Install all required prerequisite dependencies:

sudo apt-get update; sudo apt-get install make build-essential libssl-dev zlib1g-dev \
libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm \
libncursesw5-dev xz-utils tk-dev libxml2-dev libxmlsec1-dev libffi-dev liblzma-dev

Download and execute installation script:
```
curl https://pyenv.run | bash
```

Add the following entries into your ~/.bashrc file:

# pyenv
export PATH="$HOME/.pyenv/bin:$PATH"
eval "$(pyenv init --path)"
eval "$(pyenv virtualenv-init -)"

Restart your shell:
```
exec $SHELL
```
Validate installation:
```
pyenv --version
```

Uninstallation:

Remove the ~/.pyenv folder
```
rm -fr ~/.pyenv
```

Delete the following entries from your ~/.bashrc file:

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

Restart your shell
```
exec $SHELL
```

Basic commands:

To install specific version use install flag:
```
pyenv install 3.8.0
```
To list all available installed versions of Python on your system:
```
pyenv versions
```
To set a specific version of Python global (system-wide) use global flag:
```
pyenv global 3.8.0
```
To set a specific version of Python local (project-based) use local flag:
```
pyenv local 3.8.0
```