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System z is IBM's mainframe architecture (the hardware). z/OS is the flagship operating system. It is at its heart a batch-oriented system, but it does have a

by krylon 11y ago

System z is IBM's mainframe architecture (the hardware). z/OS is the flagship operating system. It is at its heart a batch-oriented system, but it does have a Unix subsystem (called USS for "Unix System Services", formerly known as MVS OpenEdition or OMVS) that is in fact certified against a rather old version of the Single Unix Specification. So in a way, z/OS is in fact a Unix system, but that is kind of like saying that Windows is a Unix due to Cygwin or Microsoft's Services for Unix. Mostly, it is very non-Unix-like. Interestingly, IBM also offers a number of other operating systems for System z, including VM (although that system apparently does little but host virtual machines), TPF (a "real-time" transaction processing system) and zVSE (formerly known as DOS/360, another, smaller batch-oriented system). And, of course, Linux is available from a number of distributions. Oh, and just for good measure, Open Solaris was ported to run inside VM, although I am not sure what became of that or if anyone is actually using it.

donatj 11y ago
What is using it like? Command line? Would it be familiar-ish to someone with Unix / DOS experience or totally foreign?
- Karunamon 11y ago
  All command line, and totally foreign on a level that makes switching from Windows to Linux look trivial by comparison. (which coincidentally, is why I want to explore it) Here's the official IBM "for dummies" book: https://www.redbooks.ibm.com/redbooks/pdfs/sg246366.pdf https://www.redbooks.ibm.com/redbooks/pdfs/sg246366.pdf
  - marktangotango 11y ago
    It uses the 3270 terminal (xterm has a 3270 mode I've used), interface is predominantly 'ispf', it's essentially menu driven; you can browse/search the filesystem, edit files, submit jobs (everything is a job ie jcl ie job control language; compile, run programs etc) browse job spools (stdout from a job). Google will show you images of ispf, browsing the jcl manuals will give you nightmares.
    - dodders 11y ago
      My first job was writing JCL decks - it's not that bad.
      - krylon 11y ago
        It is not terrifying per se, just ... very different. I have only had brief contact with JCL, but I remember having to figure out how to get a command line into JCL that was more than 80 characters in length. It took me two days to figure that out, and none of the old-timers in the team had ever had to do that. When I did find the solution, it was surprisingly simple, but finding it took me a lot of time.
nickpsecurity 11y ago
Wait, is it a UNIX system or have a UNIX subsystem? Those are different. I know it has the subsystem. I'm trying to recall when someone said it was a UNIX. Stuff I read on it is more MVS than UNIX. Example with some data: https://en.wikipedia.org/wiki/Z/OS https://en.wikipedia.org/wiki/Z/OS
- cbd1984 11y ago
  It has a Unix subsystem. It is a lineal descendant of OSes which predate Unix by quite a bit, and has grown by accretion since then. It's POSIX certified. Linux isn't. That should tell people quite a bit about POSIX, but it never seems to...
  - nickpsecurity 11y ago
    Lol at the last line. No doubt.
  - mcosta 11y ago
    Linux is just the kernel. Distributions should certify. And I do not see anyone going fot it. There is at least one distribution posix certified: Inspur K-UX. The equivalence in linux land should be LSB, which many distributions certify to.
  - LukeShu 11y ago
    POSIX isn't actually about operating systems. POSIX (1003.1) is about source-level compatibility for 2 languages: C99 and shell scripts. If your C programs use only C99+POSIX facilities, and your shell programs use only POSIX features and utilities, and they work on a platform, then that platform is eligible to be POSIX certified. POSIX doesn't care about the kernel or syscalls or anything like that. It cares about libc, libm, libl, and a couple of file paths.
    - pjmlp 11y ago
      Actually to a certain extent, I think one could call POSIX the actual C runtime library. As C runtime + POSIX calls (I know it didn't exist back then) is what defined C when it was still UNIX only, but ANSI didn't want to make the language standard that big.

by krylon 11y ago

donatj 11y ago

What is using it like? Command line? Would it be familiar-ish to someone with Unix / DOS experience or totally foreign?

Karunamon 11y ago
All command line, and totally foreign on a level that makes switching from Windows to Linux look trivial by comparison. (which coincidentally, is why I want to explore it) Here's the official IBM "for dummies" book: https://www.redbooks.ibm.com/redbooks/pdfs/sg246366.pdf https://www.redbooks.ibm.com/redbooks/pdfs/sg246366.pdf
- marktangotango 11y ago
  It uses the 3270 terminal (xterm has a 3270 mode I've used), interface is predominantly 'ispf', it's essentially menu driven; you can browse/search the filesystem, edit files, submit jobs (everything is a job ie jcl ie job control language; compile, run programs etc) browse job spools (stdout from a job). Google will show you images of ispf, browsing the jcl manuals will give you nightmares.
  - dodders 11y ago
    My first job was writing JCL decks - it's not that bad.
    - krylon 11y ago
      It is not terrifying per se, just ... very different. I have only had brief contact with JCL, but I remember having to figure out how to get a command line into JCL that was more than 80 characters in length. It took me two days to figure that out, and none of the old-timers in the team had ever had to do that. When I did find the solution, it was surprisingly simple, but finding it took me a lot of time.

nickpsecurity 11y ago

Wait, is it a UNIX system or have a UNIX subsystem? Those are different. I know it has the subsystem. I'm trying to recall when someone said it was a UNIX. Stuff I read on it is more MVS than UNIX. Example with some data: https://en.wikipedia.org/wiki/Z/OS https://en.wikipedia.org/wiki/Z/OS

cbd1984 11y ago
It has a Unix subsystem. It is a lineal descendant of OSes which predate Unix by quite a bit, and has grown by accretion since then. It's POSIX certified. Linux isn't. That should tell people quite a bit about POSIX, but it never seems to...
- nickpsecurity 11y ago
  Lol at the last line. No doubt.
- mcosta 11y ago
  Linux is just the kernel. Distributions should certify. And I do not see anyone going fot it. There is at least one distribution posix certified: Inspur K-UX. The equivalence in linux land should be LSB, which many distributions certify to.
- LukeShu 11y ago
  POSIX isn't actually about operating systems. POSIX (1003.1) is about source-level compatibility for 2 languages: C99 and shell scripts. If your C programs use only C99+POSIX facilities, and your shell programs use only POSIX features and utilities, and they work on a platform, then that platform is eligible to be POSIX certified. POSIX doesn't care about the kernel or syscalls or anything like that. It cares about libc, libm, libl, and a couple of file paths.
  - pjmlp 11y ago
    Actually to a certain extent, I think one could call POSIX the actual C runtime library. As C runtime + POSIX calls (I know it didn't exist back then) is what defined C when it was still UNIX only, but ANSI didn't want to make the language standard that big.