Comment by umanwizard
8 hours ago
Linux is quite different from macOS in many ways. They are both distantly inspired by "unix" (and Apple has managed to convince someone to let them use the trademark, so they really "are" unix, legally at least), but the similarity ends there.
They didn't convince anybody of anything. They poured an enormous amount of technical work [1] into making it compliant with the Single Unix Specification [2].
> The standard specifies programming interfaces for the C language, a command-line shell, and user commands.
What else would be necessary to call it such?
[1] https://www.quora.com/What-goes-into-making-an-OS-to-be-Unix...
[2] https://en.wikipedia.org/wiki/Single_UNIX_Specification#macO...