So, in one of my projects/products/services, I need to execute ffmpeg via PHP…
Usually I use at do send the job to a queue list.. unfortunately in two different clients’ servers somehow PHP + exec and at doesn’t work well….

This is how we send a PHP exec to background

exec(command > /dev/null 2>/dev/null &);

 

As seen on http://stackoverflow.com/questions/8961470/how-to-make-shell-exec-run-in-background-while-php-continues