Learning about "The Unix Time-Sharing System"(playtechnique.io)
14 pointsby gwynforthewyn2 hours ago2 comments
  • gwynforthewyn2 hours ago
    I'm the writer of this essay.

    My subject is some details surrounding the first white paper that Bell Labs published about Unix was "The Unix Time-Sharing System". I wrote what Ken Thompson was doing in between the end of Multics but before he found the "little used PDP-7" that he wrote Unix on, the difference between opening files on Multics and Unix, and what the "comfile" mentioned in the paper is.

    I wrote this without AI involvement; I follow Unix history because I love knowing what the history is and what I can learn from it, and I love showing others these sorts of cool details.

    I'd love to hear any feedback you might have :)

  • bchan hour ago
    > So what's a comfile? Clearly it's a shell script, yeah? So why're they called comfiles? It's short for "command files".

    The vestige I'm amused by on my (BSD) systems is <foo>.S files. "S" for "Source". From the time when "source code" meant "assembly". Python, zig, C++, C, etc would be invented later...

    • gwynforthewyn8 minutes ago
      I <3 the BSDs, and they're the reason that the quote from "A Research Unix Reader" stuck in my memory! I started on the linuxes, pre-systemd by many years, and remember system v init levels seeming straightforwards but weird. When I switched to FreeBSD and saw /etc/rc.local, it made far more sense to me. I never even _thought_ about what 'rc' might mean, though.

      Seeing the quote from Doug McIlroy many years later lodged in my brain as answering a question I didn't even have, and I've been looking for a good reason to use it ever since.

      There's a lot of cool small details like that in so many early white papers about Unix; I'm looking forwards to working through a good number of them over the next 12 months. I think next I'll look at Dennis Ritchie's paper on the impact of migrating Unix from assembly to C. It may give me good opportunity to cover the B->C change as background, which is fascinating to see.