How to install and enable PHP 5.5 extensions

Question

I am setting up Flarum forum software, I would like to install mbstring, pdo_mysql, openssl, json, gd, dom, fileinfo at once, as the instructions say, I need these.

Answer 1

These are called modules / extensions and can be enabled in the php.ini

Possible duplicate of Fatal error: Call to undefined function openssl_random_pseudo_bytes()