I've got a set of RewriteCond rules that test for various mobile devices and then set environment variables like "env=device:.iphone" or "env=device:.smartphone" if the useragent matches an iPhone or Android device.
I'm trying to now redirect the user to custom-styled 404/500 server error pages for each device, by way of the error pages.
Ideally I'd like to be able to test for a variable being there, and then write in a custom ErrorDocument string. But an apache doesn't seem to work in this case.
Any ideas how I can construct if/else tests in an apache conf file for environment vars?