Thank you very much! I have setup the win32::readdirectorychangesw module on my hard drive by copying the pm file to the directory of perl. i tried the following code as you told me:

use strict;
use warnings;
use File::Copy::Recursive qw(fcopy rcopy dircopy fmove rmove dirmove);

use Win32::ReadDirectoryChangesW;

my $path    = 'c:\\PAPER';
my $subtree = 1;
my $filter  = FILE_ACTION_ADDED | FILE_ACTION_MODIFIED;

my $rdc = Win32::ReadDirectoryChangesW->new(path   => $path,
                                            subtree => 1,
                                            filter  => $filter);
  
my @results = $rdc->read_changes;

while (scalar @results) {

   my ($action, $filename) = splice(@results, 0, 2);
 
   if ($action == FILE_ACTION_ADDED || $action == FILE_ACTION_MODIFIED
+) {

      # perform your backup here
      fcopy ("$filename","p:\\phdpaper");

   }

}
[download]

But i got a wrong message: Bareword "FILE_ACTION_ADDED" not allowed while "strict subs" in use at C:\PAPER\1.pl line 9. Bareword "FILE_ACTION_MODIFIED" not allowed while "strict subs" in use at C:\PAPER\1.pl line 9. Bareword "FILE_ACTION_ADDED" not allowed while "strict subs" in use at C:\PAPER\1.pl line 21. Bareword "FILE_ACTION_MODIFIED" not allowed while "strict subs" in use at C:\PAPER\1.pl line 21. Execution of C:\PAPER\1.pl aborted due to compilation errors.

Then i delete the "use strict" script, runing...., but still got the following error: Can't locate object method "new" via package "Win32::ReadDirectoryChangesW" (perhaps you forgot to load "Win32::ReadDirectoryChangesW"?) at C:\PAPER\1.pl line 11.

So, can you help me figure out what the problem was? Thanks a lot!