How to install newer PHP versions on our Debian 9 (Stretch) LAMP server in PHP-FPM mode
The official repository for Debian 9 (Stretch) has PHP 7.0.x, which is a bit out of date, and you won't receive any updates. Therefore, we may need newer versions if we run live websites, but we can even expand our test environment. In this description, we will conveniently install several versions of PHP using the deb.sury.org external repository, which can be run side-by-side on our Debian-based servers using the PHP-FPM server API.