This is a bash script for switch between PHP versions that are enable as Apache2 webserver module.

exphp

#!/bin/bash
sudo update-alternatives --set php "/usr/bin/php$2";
sudo update-alternatives --set "php-config" "/usr/bin/php-config$2";
sudo update-alternatives --set phpize "/usr/bin/phpize$2";
sudo a2dismod "php$1"
sudo a2enmod "php$2"
sudo service apache2 restart

You can use it with the following command:

chmod +x path/to/file/exphp
path/to/file/exphp 5.6 7.2

This will switch PHP5.6 to PHP7.2.