Re: How to monitor a directory in FreeBSD?

On 13.08.2022 15:16, meator wrote:
> Hello. I'm working on a C program that needs to know whether files and 
> directories in a specific directory were added, modified or deleted. (It should 
> also be done recursively for all subdirectories, but to keep it simple I don't 
> take recursion into account. It shouldn't be that hard to implement it after I 
> will be able to monitor a directory nonrecursively.)
> 
> I don't have much experience with BSD programming but I know POSIX. I have used 
> inotify before for this purpose, but BSD doesn't have it so I started looking 
> for BSD alternatives. The internet lead me to kqueue. I saw some criticism of 
> it, but I don't need to monitor several thousands of files, so I hope it will be 
> usable for my use case.
> 
> The EVFILT_VNODE filter documentation in kqueue(2) doesn't really talk about 
> files and directories, it talks about file descriptors. Inotify on the other 
> hand is very explicit about handling files in the monitored directory. Kqueue 
> can still detect creation and deletion of files inside the monitored directory 
> with NOTE_WRITE for files and NOTE_LINK for directories (at least I think, I 
> made a little test program to test this).
> 
> This is useful, but I don't see any obvious way to identify a newly created file 
> inside the monitored directory. File creation would result in NOTE_WRITE, but 
> struct kevent doesn't have any "name" field (unlike inotify) that would show 
> which file was created. I would have to make a list of directories and compare 
> the old state with the current state to see the file which was added.
> 
> Kqueue also doesn't seem to detect modification of files inside the monitored 
> directory. Does this mean that I would have to monitor every single file in the 
> directory to make this work?
> 
> I think this shows that kqueue isn't really meant to be used for monitoring 
> directory members. Is this true? Have I misunderstood something?

It looks that inotifywait from sysutils/inotify-tools is what you need

-- 
WBR
Vladimir Kondratyev