MacOS – How to Monitor a Folder for Changes or Activities

If you take interest in the command line:

find / -type d -name "*farm-animal-type*"

you can change the starting area from / to whatever you want if you have a good idea of where the folder is generally located. Spotlight will be much snappier as the folders are indexed though.

To work around "operation not permitted" errors, use the Time Machine Safety Net "bypass" program:

sudo /System/Library/Extensions/TMSafetyNet.kext/Contents/MacOS/bypass rm -rfv /Volumes/[disk]/Backups.backupdb/[path]

In 10.8 Mountain Lion, bypass moved into 'Helpers':

/System/Library/Extensions/TMSafetyNet.kext/Helpers/bypass

In 10.10 Yosemite, bypass moved here:

/System/Library/Extensions/TMSafetyNet.kext/Contents/Helpers/bypass

Beware when using this to delete specific snapshots: as Time Machine uses hard links, using rm -r on folders might also affect older and newer snapshots of the same machine. (See other answers referring to tmutil delete to safely delete a specific snapshot.) Using rm to delete all snapshots for a single machine is okay though. And so is using rm to delete a specific file, which will only remove that hard-linked file from the snapshot(s) you specify, assuming the file is not in a hard-linked directory as then you'd actually remove the file from all those hard-linked directories.