To anyone who has an Apple notebook with Time Machine enabled and a few hours of uptime, please run the following command:

cd ; sudo find /.MobileBackups -type f -print ; sudo lsof /.MobileBackups

– I'd like to know whether the list of open files at that path is similar to the list of files. Thanks

I can enable local and test in a few hours, @GrahamPerrin

Are you checking for open files before you have find trawl the filesystem?

In a quick check - I have 19 files in the filesystem and 0 from lsof but a backup interval hasn't arrived yet.

I get the feeling that weird voodoo happens in that virtual filesystem, though

bmike$ sudo find /.MobileBackups -type f -print | wc -l ; sudo lsof /.MobileBackups | wc -l
      96
       0

@bmike - test reply... Looking good :)

@bmike from results a day or so ago, I had a hunch that /.MobileBackups (in the HFS Plus file system) might somehow relate to files that were open; that could not be moved (for want of a better expression) to the mtmfs file system that's mounted at /Volumes/MobileBackups

When I discover how the OS uses the two areas in concert, I'll add an answer to apple.stackexchange.com/q/21435/8546

@mark-adler apple.stackexchange.com/questions/207641/… for the future, please consider placing a bounty instead of cross-posting.

Also please for convenience please add a link from the cross-post to the question in Ask Different; unix.stackexchange.com/questions/232362/… is noted but I had to spend a couple of minutes searching before I found the cross-post. Thanks.

To any user of OS X: is unix.stackexchange.com/a/265005/13260 good for you?

It's not good for me; pastebin.com/P6if9DEB