scalable directory and file change notification

 inotify (inode notify) is a Linux kernel subsystem that monitors events in
 filesystems and reports those events to applications in real time.
 .
 inotify can be used to monitor individual files or directories. When a
 directory is monitored, inotify will return events for the directory itself
 and for files inside the directory.
 .
 This module implements an interface to the Linux 2.6.13 and later inotify
 directory and file change notification system.
 .
 It has a number of advantages over the Linux::Inotify module:
   - It is portable (Linux::Inotify only works on x86).
   - The equivalent of fullname works correctly.
   - It is better documented.
   - It has callback-style interface, which is better suited for integration.