Trick of the day: monitoring the Linux filesystem changes in “real time”

Ever wanted to monitor the filesystem changes ?

Since Linux 2.6.25, the kernel provides us with a signal driven I/O notification API and the inotify-tools RPM provides a set of tools to interact with the kernel.

inotify in action: a simple way to test this API is to run the following command in a terminal window:

% inotifywait -m /tmp
Setting up watches.
Watches established.

in another terminal window, just create a file in /tmp

% touch /tmp/toto

The inotifywait output should be:

/tmp/ CREATE toto
/tmp/ OPEN toto
/tmp/ ATTRIB toto

Of course, the output can be filtered using the -e|–event argument, etc… (see the inotifywait or inotifywatch man pages).

inotify-tools can be used as-is in batch files, allowing you to define your own surveillance programs. Of course the kernel API is available for other programming langages, C of course, but also python (python-inotify.noarch RPM), perl (perl-Linux-Inotify2 module), ruby (rubygem-rb-inotify gem).

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