macOS is basically already a POSIX subsystem for macOS, which is already a UNIX™. But (some) people still criticize it because it's not Linux or FreeBSD (thoug

macOS is basically already a POSIX subsystem for macOS, which is already a UNIX™. But (some) people still criticize it because it's not Linux or FreeBSD (though it is closer to the latter than the former).