Documentation changed to match the bug, seldom-used features that no longer work, and malware protection that devoured parts of Xcode.
union
Union mounts let you merge the contents of two volumes without copying any files. Do they work as expected in Sonoma’s APFS, though?
Other file systems, with an outline of vfs and vnodes used by the kernel, and how they’re important in checking code signatures.
The Eclectic Light Company 