A class for monitoring events related to files and directories. This package is deprecated in favor of win32-changejournal on NTFS filesystems.


* Ruby 1.8.0 or later
* win32-ipc 0.4.0 or later


rake test (optional)
rake install (non-gem) OR rake install_gem (gem)


require 'win32/changenotify'
include Win32

# Indefinitely wait for a change in 'C:\some\path' and any of its
# subdirectories.  Print the file and action affected.

filter = ChangeNotify::FILE_NAME | ChangeNotify::DIR_NAME
path   = 'C:\some\path'
cn =, true, filter)
cn.wait{ |arr|
   arr.each{ |info|
      p info.file_name
      p info.action
# OR, true, filter) do |events|
	events.each{ |event|
		p event.file_name
		p event.action


The Win32::ChangeNotify class is a subclass of Win32::Ipc, and thus has
all of its methods available as well.

This library is deprecated in favor of win32-changejournal on NTFS
For additional documentation please see the 'changenotify.txt' file under
the 'doc' directory.

Pure Ruby vs C Extension

The C code we used for this library prior to 0.5.0 is still available in CVS for this project, but is not distributed with official releases. Note that it does NOT contain the completion port approach we use in 0.5.0 and later and is actually less reliable (in terms of how many simultaneous events it can pickup) as a result.

Known Issues

Despite the improvements yielded as a result of using completion ports,
it's still possible that events could be missed. To be more precise,
any events that occur in the fraction of a second between the call to
GetQueuedCompletionStatus() and ReadDirectoryChangesW() in the wait loop
will not get picked up. As a general rule, the faster your system is,
the less likely you are to encounter this scenario.
We do not believe it is possible to resolve this issue without native
thread support. We are, however, open to suggestions. :)


This class was originally based on the Win32::ChangeNotify Perl module by
Christopher Madsen.

Future Plans

Probably none. This library is deprecated in favor of win32-changejournal.
However, that library only works on NTFS filesystems, so this package will
be maintained as well.
That being said, I'm always open to improvements, so feel free to submit
ideas and patches.

Known Bugs

None that I know of. Please log any other bug reports on the RubyForge
project page at




(C) 2003-2007 Daniel J. Berger, All Rights Reserved


This package is provided "as is" and without any express or
implied warranties, including, without limitation, the implied
warranties of merchantability and fitness for a particular purpose.


Park Heesob
Daniel J. Berger