I found myself constantly needing to switch PHP versions in my development environment based on the projects I work on. I wanted to have a simple way to switch php versions and all the tools I found were heavy weight or to complicated for my purpose. So I wrote a simple bash script which provides a list of available PHP versions and allows you to switch between those versions. This script is written for Ubuntu and tested in Ubuntu 16.04.
You can download the script from my github gist.