I have installed PHP v7.2. when I do php -v in my terminal, I get:
$ php -v
PHP 7.2.0-2+ubuntu16.04.1+deb.sury.org+2 (cli) (built: Dec 7 2017 20:14:31) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.2.0, Copyright (c) 1998-2017 Zend Technologies
with Zend OPcache v7.2.0-2+ubuntu16.04.1+deb.sury.org+2, Copyright (c) 1999-2017, by Zend Technologies
Which php, gives me, /usr/bin/php?
But there is no php.ini in that directory. How can I find the location of php.ini?

locate php.iniwill search for it. Though you also will need to update it withupdatedbonce after installing (the database is not realtime to speed searching up by a lot). – Rinzwind Jan 03 '18 at 10:20sudo. – Rinzwind Jan 03 '18 at 12:22