Delete file after download

Aha, yeah, that'd be it, well done.

I suppose in most cases it would make sense there is no additional output once you send the file, because that would end up in the end of the file on users harddrive.

You only need couple of header() calls to make browser download the file, so you can write your own version of force download function, or alternatively you could write cron job that goes and cleans files off once their old enough to def not be in use anymore.