custom module of Joomla

I want to access the configuration.php file from a custom front-end module. I want to set "var $offline" to o or 1 from the module(through radio) a开发者_StackOverflownd then refresh page. i also want the module to show when the site is off line.

You do not want to access the configuration.php directly. Instead, use the functions joomla provides to change the website into maintenance (/offline) mode.

Maintenance will not allow you to specify displayed modules. You will need to change Joomla to include it or custom code in maintenance mode.