^ click above ^

Many modern systems provide a way to watch a directory for events (new files, reading the directory, modification of a file in the directory, etc.). This facility can be done in various ways, from providing hooks in the filesystem code itself to something that watches for inode changes. Linux and BSD have several possibilities in that regard, including dnotify, changedfiles, and watch.

#!/usr/bin/perl
@info=stat("testdir") or die "Can't stat testdir $!";
while (1) {
@newinfo=stat("testdir") or die "Can't stat testdir $!";
@what=qw(Device Inum Mode Links Owner Group Rdev Size Atime Mtime Ctime 
    PBlock Blocks);
$x=0;
while ($info[$x]) {
  system("/bin/echo $what[$x] $info[$x] $newinfo[$x]") if ($info[$x] 
    ne $newinfo[$x]);
  $x++;
}
@info=@newinfo;
sleep 1;
}