dnotify

dnotify is a file system event monitor for the Linux kernel, one of the subfeatures of the fcntl call. It was introduced in the 2.4 kernel series.^[1] It has been obsoleted by inotify, but will be retained for compatibility reasons.

Its function is essentially an extension to

to notice changes to the filesystem, and report those changes to applications. Instead of application checking for changes to filesystem, application can register to be notified by kernel when changes to filesystem occur. Application can select directories to monitor and types of changes to be notified for.

One major use is in

functionality).

Limitations

• dnotify can only watch directories.
• dnotify requires maintaining an open file descriptor to the directory that the user wants to watch. First, the directory is open, hence disallowing the device on which it resides from being unmounted. Second, watchlist is limited by open file limit of the process.^[2]

See also

• Linux kernel API
• File alteration monitor
• inotify, a dnotify replacement.
• The Documentation/filesystems/dnotify.txt file in the kernel source tree

Footnotes