Homebrew

If it’s not already done, you first have to install Homebrew, a package manager for macOS.

$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Install a specific version of PHP

To install a specific version of PHP, you simply have to use the keyword install following the package containing the PHP version of your choice, without the dot.

For example, if you want to install PHP 5.6:

$ brew install php56

And if you want to install PHP 7.2:

$ brew install php72

Choose the PHP version you want to use

To choose a PHP version to use, you just have to link the package of the version of PHP of your choice.

For example, if you use PHP 7.1, and you have installed PHP 5.6, PHP 7.0 and PHP 7.1, but you want to use PHP 5.6:

First, unlink the php version actually linked:

$ brew unlink php71

Then, link the version you want to use:

$ brew link php56

If you want to come back on PHP 7.1, unlink PHP 5.6 and link PHP 7.1: