While installing a new perfect server (Ubuntu 16.04) and because Ubuntu 16.04 comes with php7.0, At the end I get the system with php7.0 (only) which is incompatible with most of websites now. So I need to install php5.6 alongside with php7.0. (as I know) The best source of php5.6 is the PPA (https://launchpad.net/~ondrej/+archive/ubuntu/php) which contains three versions 5.6, 7.0 & 7.1. The problem is, after adding the PPA and trying to install/update the system apt/aptitude forces installing of php7.1 which I don't want, I want to stay with version 7.0 from Ubuntu to get the official updates, and I want php5.6 (only) aslo. I don't want version 7.0 nor 7.1 from the PPA. How to avoid php7.0 & php7.1 from the PPA ?