[mdlug] How reliable is inotifywait?

[Mark Montague]

Hi, Steve,

inotifywait is very reliable except in edge cases -- read the inotify(7) 
man page for details.

You may want to look at Watchman ( https://facebook.github.io/watchman/ 
).  Watchman attempts to be as conservative as possible, and if it 
thinks events might have been dropped, it re-scans the 
directory/directories to be sure. However, Watchman has separate service 
and client parts as well as more dependencies, so it may or may not be 
suitable for your use case.

Personally, I think inotifywait is suitable in most cases, and 
preferable in many cases, particularly if you increase the Linux inotify 
limits ( 
https://facebook.github.io/watchman/docs/install#linux-inotify-limits )

--
Mark Montague


On 2024-03-10 18:08, Steve Litt wrote:
> Hi all,
>
> The inotifywait program waits until a specific file event happens in a
> specific directory or file, and then terminates. So it enables
> file-driven event driven programs.
>
> I'd like to wake up the instant a file appears in a directory.
> Something like the following:
>
> inotifywait -e create -e moved_to -t 30 /tmp/pager
>
> The preceding waits 30 seconds, except if a file is created in or moved
> to /tmp/pager, it quits waiting and terminates immediately.
>
> I use it to combine polling with an event driven, so if for some reason
> the event (moved_to or create) doesn't quit and terminate immediately,
> it will still quit and terminate at the end of 30 seconds.
>
> I can significantly simplify my program if I changed -t 30 to t -1,
> where -1 stands for "forever". False positives aren't a problem: They
> would just start another cycle. But false negatives, where a file is
> created or moved into /tmp/pager but fails to quit and terminate, would
> really mess me up in this particular situation.
>
> So what do you think, is inotifywait reliable?
>
> Thanks,
>
> SteveT
>
> Steve Litt
>
> Autumn 2023 featured book: Rapid Learning for the 21st Century
> http://www.troubleshooters.com/rl21
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