feature request: support Cache Directory Tagging Specification

[calestyo]

Hey.

This had already been asked previously on the mailing list and a similar solution (-F) had been presented there.

However, I think it would still be nice if rsync could support the Cache Directory Tagging Specification, which basically boil down to, any directory that contains the file CACHEDIR.TAG with the content Signature: 8a477f597d28d172789f06886806bc55 (and optionally some more, see the specs) is not backuped (or on the cased of rsync considered for copying).

Apart from avoiding possible side effects of -F (which AFAIU has the side effects of --trust-sender), the main benefit would IMO be interoperability. Other tools (e.g. dar via its --cache-directory-tagging option) already support CACHEDIR.TAG, so it would be just nice to be able to use it with rsync to, without having to manually "re-build" it with -F.

Thanks for consideration, Chris

[jkt628]

it would be nice to have --exclude-caches and variants from GNU tar, which were added there back in 2007.