If your "path of interest" contains symlinks to directories on other disk volumes or partitions, and if it turns out that some of the symlinks point to non-existent or unavailable paths (e.g. pointing to a volume that isn't currently mounted), one solution would be to stick with my 3-step procedure (and still don't use  -follow in the find command at step 1), but subdivide step 2 into a few separate steps:

• 2. For each directory, scan its immediate contents with readdir()

  • 2.a. Accumulate data files and symlinks in separate lists

  • 2.b. For each element of the symlink list, determine its target, determine whether the target exists, and if so determine whether it is a data file, a directory, or another symlink. The output listing for the directory currently being scanned should contain just this information about the symlinks.

  • 2.c. For each element of the data file list, get the other stat info you need and report this in the listing for the current directory.

Based on that treatment, you'll know whether symlinks have been added or removed from within the directory tree of interest, you'll know which ones are broken, and for the ones that work, you'll know what sort of thing they point to, and (comparing listings from consecutive days) whether there has been a change in their target path. That should be all you need to know about symlinks per se.

For the ones that work, you won't know from the symlink listing whether the content of the target path has changed (i.e. change of a data file or change of directory contents). But if the target is a datafile or directory within the current tree of interest, that information will be available elsewhere in your overall output.

And if the target is on some other disk volume/partition, running this same process on that volume (on the relevant directory tree of interest) will tell you what you want to know about that content.

There will be some serious work in keeping all this information organized and managed properly, to make sure that everything gets covered with (ideally) no redundancy -- e.g. a process that scans the output listings for a given directory tree and launches this same process on other volumes as needed to cover all the cross-volume symlinks. I'll leave that as an exercise. ;)

(Good luck with the case of "symlink points to symlink points to symlink...", and with cases of "relative" as opposed to "absolute" target paths. You may need to do the equivalent of bash's "pushd / popd" within your perl script to test for target existence of relative-path symlinks.)