Periodic toot about my astonishment that a lot of “techies” don’t know that macOS is a true UNIX operating system going back in a direct line to the original UNIX (and BSD). ¯\_(ツ)_/¯
@thomasfuchs I sort of incidentally figured out that MacOS is a UNIX OS under the hood whenever you use the Terminal. It screams UNIX (and even uses the same commands and functionality as any other UNIX terminal).
@thomasfuchs well it's not entirely a Unix to me, as it doesn't use X11 (but I guess Unix existed before that), and it doesn't use a monolithic kernel (but maybe I'm biased by the book I read about Unix kernel design) 🤷
@mxk@brouhaha Net/FreeBSD are 90s implementations of BSD.
NeXTSTEP predates these by almost a decade and is based mainly on Mach (80s reimplementation of BSD kernel) and also the original BSD, directly, itself.
Darwin (macOS core) later added more parts from other BSDs.
The original BSD itself is based on the original Bell labs Unix source code.
Thus, there is a direct line back to the original 1969-era Unix.
@thomasfuchs AFAICT, vanishingly little of MacOS X (now macOS), probably not even a single line of code, came from original Unix. That doesn't seem like a "direct line" to me, but rather a meander all over the place. Reminds me just a tiny bit of the widespread (but spurious) claims that QDOS/86DOS/MS-DOS/IBMDOS was built on code from CP/M.
@brouhaha@thomasfuchs this. It is certified Unix compatible and it at different points incorporated code from NetBSD and FreeBSD, but XNU/Darwin Trace no direct history to the AT&T Unix/System V, so calling it a "true" Unix is misleading. And in a world where the true Unixes all are dead, the value of this certification is really questionable. I would argue, that POSIX nowadays is what counts, and certified UNIX is purely a gimmick.
@thomasfuchs@brouhaha Modern BSDs depending on how you draw the line starting with Net/2 or with 4.4BSD-Lite Release 2 are legally and logically separate from their original Unix history and should be considered reimplementations. Also, those are just drivers and subsystems that are borrowed from and not the Kernel. XNU/Mach never were part of the main Unix family. And using drivers and the network stack from BSD is in no way unique to MacOS, QNX and Windows NT did the same.