Here's a one-liner for you:

perl -e '-e $ARGV[0] ? sleep 10 : die "GONE!" while 1' <FILENAME>
[download]

Of course, the complexity of your final script depends entirely on what you want to do when the file disappears, which you haven't quite stated...

   MeowChow                                               
                print $/='"',(`$^X\144oc $^X\146aq1`)[-2]