macOS is BSD Unix under the hood with the Mach kernel [1]. I'm tired of hearing this nonsensical talking point that macOS has strayed too far to be considered Unix. What does that even mean? Perhaps someone should inform The Open Group who controls the official Unix specification that they are wrong. Even though it shells like a unix, users like a unix, signals like a unix, files like a unix, networks like a unix, streams like a unix, and threads like a unix, because of reasons never enumerated, macOS is not Unix. /endrant

[1] https://developer.apple.com/library/mac/documentation/MacOSX...

Because, with the popularity of Linux, people have forgotten how varied unix-like OSes once were. I'm sure the grandparent poster will mention things like how it stores configuration differently, etc, but that's only not-unix-like to someone who hadn't used a handful of different commercial Unices back in the 1990s.

For me, they key pieces are: 1) frameworks. when traditional search paths don't find executables and dyn libs the way you expect, it isn't unix-alike. 1a) when the execution environment has changed enough that the build needs to be modified beyond a few simple config variables, it isn't Unix-alike. 2) unconventional init system. although BSD is moving to something similar to launchd, so I think that idea is evolving toward mainstream. 3) unconventional cron, see launchd/BSD.

So dll dependencies are crazy-making, and Nix is attacking that. traditional init is getting creaky, launchd and systemd are attacking that.

With respect to systemd, I love how it has motivated people to try to come up with something better than both traditional init and systemd.