Linux Filesystem event notification using inotify

inotify is a file change notification system—a kernel feature that allows applications to request the monitoring of a set of files against a list of events. When the event occurs (read, write, create, delete,mount, un-mount, etc ..), the application is notified. To be useful, such a feature must be simple to use, lightweight with little overhead and flexible. It should be easy to add new watches and painless to receive notification of events.

This can be a handy tool if you need to monitor some directory for files update and as soon as it got updated you need to do some operation.

There is a tool called inotify-tools, which is a C library and a set of command-line programs for Linux providing a simple interface to inotify

Installation:

Fedora
inotify-tools is available through the Fedora Extras repository. Just do: yum install inotify-tools

Gentoo
inotify-tools is available in Gentoo's official portage tree. It may be masked, in which case read the "MASKED PACKAGES" section of the man page for emerge, then unmask it. Then you can simply: emerge inotify-tools

Ubuntu
sudo aptitude install inotify-tools

Othere
you can donload the source code : here and compile and build your binary using following command
./configure --prefix=/usr && make && su -c 'make install'

Some of the events that can be monitored for are:

IN_ACCESS - read of the file
IN_MODIFY - last modification
IN_ATTRIB - attributes of file change
IN_OPEN and IN_CLOSE - open or close of file
IN_MOVED_FROM and IN_MOVED_TO - when the file is moved or renamed
IN_DELETE - a file/directory deleted
IN_CREATE - a file/directory created
IN_DELETE_SELF - file monitored is deleted

Java api - here