title: How does Mac OS X know what programs are using a mounted filesystem?
body: <p>This may sound like a silly question but up until recently if you tried to unmount a volume that was in use the Finder reported that it was in use, but not by whom.  This is simple Unix functionality, if a file is open on a mount point, do not allow it to eject.  But now they seem to have added functionality that lets the user know what programs are currently using a mounted system, and I have been looking through man pages of fopen,stat, etc. for Unix like operating systems(distros of linux) and I can't seem to find similar functionality.</p>
  
  <p>Is this functionality specialized, or am I just looking in the wrong place?</p>