Well, that very much depends on the UNIX in question. If one defines UNIX as POSIX, then, for the most part, or at least a pretty good part, Linux IS UNIX, bec

Well, that very much depends on the UNIX in question. If one defines UNIX as POSIX, then, for the most part, or at least a pretty good part, Linux IS UNIX, because Linux implements much of POSIX, and in some cases does it better, e.g., certain functions for which POSIX is quiet or negative about thread safety are thread-safe on Linux, and there are almost always TS versions, e.g., strtok_r. Outside of POSIX, one has to conside OS specific features, two of which come to mind as superior, though this is a judgement call: Solaris Zones and Mac OS. I was a Linux desktop user for years, but I found that over time the desktop just started getting in my way (this was tennish years ago, so I am sure things have changed). I’d curse how gnome or KDE had once again broken my UX, then I’d help my wife or daughter with their Macs, enjoy the experience, the curse when I got back to my machine. One day, after a particularly frustrating battle with whatever desktop I had then (I’d gone from Ubuntu to Mint to Debian to I cannot remember what, trying to find the sweet spot), I cursed, yelled that I would be back in 90 minutes, and bought my first Mac. They’ve been a joy to use since. If Apple does something stupid, e.g., stopping at an old, brain dead bash, well, homebrew, et al, to the rescue. Solaris Zones were wicked. One could get full MAC with labelled networking and restricted root with ease. It’s finally possible to get close to Zones with a mix of capability management, namespace management, SELinux, et al, but not as easily. So, yeah, there are individual UNIXisms that are better than Linux, but overall, at least on the server side, Linux is UNIX improved.