PHPinfo.php in a command file in php. When run it will give you all sorts of specific details about which version of php you are running and how it is configured.

To run this command file, create a php file on your server (Example: phpinfo.php) and put the following code on it:

<?php phpinfo(); ?>

You must then navigate to the same file on your website:
Example: https://www.somewebsite.com/phpinfo.php

This will cause a page of dynamically generated configuration information to be output.

Important Note: For security purposes, you should never leave this file on your website server. This information gives out certain details about your hosting that hackers may use to help them gain access to your website.

If you must keep this file on your website then rename it to something other than phpinfo.php.

Better yet, be really tricky and create a totally fake phpinfo.php page with totally bogus information and leave it on your website. This will confuse the hackers and keep them spinning their wheels until they give up.
Example: https://www.computer-geek.net/phpinfo.php