> The functionality is key for socket-activated daemons which is a Big Idea behind systemd
https://en.wikipedia.org/wiki/Launchd#Socket_activation_prot...
https://en.wikipedia.org/wiki/Launchd#Socket_activation_prot...
I do believe that launchd came first: https://news.ycombinator.com/item?id=2565780
Perhaps I misunderstood your comment in interpreting it to say socket activation's an original systemd concept.
I was trying to respond to "Why does systemd have to store file descriptors?" with "That's actually the entire point of its existence"