How can I do non-blocking file I/O in Matlab?

I have two matlab programs/functions. One is a loop that does videoprocessing and controls a device via bluetooth. The other is a simple command processor.

If a command is entered in the command processor the information has to be conveyed to the videoprocessing loop, to influence it. But the processing should not halt. I could use a (unix) pipe to do this, but how can I read whether there is information available on the pipe? Do I really need a dedicated mex-function for this, or use the parallel toolbox where I create 2 processes communicating via a shared variable? (I hoped that fopen would have the O_NONBLOCK option, but alas ...)

Thanks for an answer,
     Sietse Achterop