In previous articles about Finder Aliases and Bookmarks, I have referred to them as opaque data structures which can be used in the Finder and accessed only in limited ways, for example using Precize to resolve Bookmarks or alisma to access them through the command line. Thanks to the work of Michael Lynn just over three years ago, we can now look inside Bookmarks and Aliases. This article uses a new version of Precize to do exactly that.
To recap: a hard link is just an additional entry in the APFS file system directory which points to the file in storage, and a symbolic link is just a file with a relative path which points to the original file (this relative path may become absolute, e.g. when the original is stored on a different volume).
Apple introduced Finder Aliases in System 7, almost 30 years ago in 1991. Prior to that, users didn’t have access to any form of link or alias, but when the largest hard disk available in a Mac was only 160 MB, that wasn’t such a problem. From the outset, Aliases have been presented as opaque data structures which are handled by the system. Although apps have been able to obtain information from them, Apple hasn’t intended any more general access to the data which they contain.
Read more at EclecticLight.co