535651 Panel that rewrites variables online on php file

I need the following application for the web, under PHP. 1. One control panel or "page" where the user can create new variables, and modify its content (numeric values). 2. Option to delete variables. 3. Option to update variables. All changes must be applied to one php, named [login to view URL] Example: I enter the system and create the variable "cars". I put its value in 3. [login to view URL] must then have the statement $cars = 3; The file must be updated for each new variable created, variable deleted, o variable updated.