Controller File Name?

I'm just starting CI on Linux and I notice that I cannot get a Controller to work properly unless the Controller file name begins with a capital letter.  IOW, a controller named "Home" will not work unless the controller's file name is "Home.php".

I've tried different combinations of "Home" and "home" for the Controller name and different combinations of "Home.php" and "home.php" for the Controller's file name.  The only file name that works is "Home.php.

I'm just trying to see if there is way to keep all file names lowercase - which is a convention I've been using for years...

Any clarification would be appreciated.

Thank you in advance.