If you are talking about custom hooks than this is something you write most likely in BASH. You can read more here how you can register/add new hooks to your cPanel:
support.cpanel.net
How to set up Standardized Hooks with BASH in cPanel & WHM
This guide is for cPanel users who have root access on their cPanel server and who would like to add custom functionality to cPanel and/or WHM using the BASH scripting language. It is important t...
