An extended attribute is a filesystem feature that is used to associate computer files with metadata. Dropbox syncs the following extended attributes:
MacOS
- com.dropbox.attributes
- com.dropbox.internal
- com.apple.ResourceFork (not synced for directories)
- com.apple.FinderInfo
- com.apple.metadata:_kMDItemUserTags
- com.apple.metadata:kMDItemFinderComment
- com.apple.metadata:kMDItemOMUserTagTime
- com.apple.metadata:kMDItemOMUserTags
- com.apple.metadata:kMDItemStarRating
- com.dropbox.ignored / user.com.dropbox.ignored/ :com.dropbox.ignored
Windows (represented as Alternate Data Streams)
- :com.dropbox.attributes
- :com.dropbox.internal
- :com.dropbox.apple.ResourceFork(not synced for directories)
- :com.dropbox.apple.FinderInfo
- :com.dropbox.apple.metadata._kMDItemUserTags
- :com.dropbox.apple.metadata.kMDItemFinderComment
- :com.dropbox.apple.metadata.kMDItemOMUserTagTime
- :com.dropbox.apple.metadata.kMDItemOMUserTags
- :com.dropbox.apple.metadata.kMDItemOMStarRating
- :com.dropbox.posix.executable
- com.dropbox.ignored / user.com.dropbox.ignored/ :com.dropbox.ignored
Linux
- user.com.dropbox.attributes
- user.com.dropbox.internal
- user.com.apple.ResourceFork(not synced for directories)
- user.com.apple.FinderInfo
- user.com.apple.metadata:_kMDItemUserTags
- user.com.apple.metadata:kMDItemFinderComment
- user.com.apple.metadata:kMDItemOMUserTagTime
- user.com.apple.metadata:kMDItemOMUserTags
- user.com.apple.metadata:kMDItemStarRating
- user.com.dropbox.foldericon
- com.dropbox.ignored / user.com.dropbox.ignored/ :com.dropbox.ignored
Note: These represent filesystem-visible attributes, and do not include attributes which are not considered “extended” attributes.
Common use cases for extended attributes in Dropbox
- Tracking synced files
- Syncing tags, stars, and colors marked in MacOS Finder
- Keeping track of files uploaded via camera uploads (on desktop and mobile)
- Supporting less-common filesystem features, like executable bits on POSIX and resource forks on MacOS
