[caslon]

Yeah, absolutely; wasn't criticizing the choice of FreeBSD more generally (short of elegant maybe, but the only real UNIX systems available these days are illumos and xv6, and they're short of elegant, too), just thought it odd for that specific use case.

Thanks for answering! That's really interesting about clisp; I've always found it a more comfortable interactive environment than any other Common Lisp, but it definitely sacrifices portability for comfort in more ways than one (lots of symbols out of the box that aren't in the HyperSpec or any other implementation, too, for example). I'm now really thankful I've never been tempted to look to its source!

[skissane]

> the only real UNIX systems available these days are illumos and xv6

I do wonder how you are defining "real UNIX system" in that statement.

[caslon]

How do you define UNIX? Don't use "a system licensed to use the trademark," as that's boring and includes many things that are definitely far from it. It's hard to pin down! I'd say it's easiest to define what isn't: massive systems.

Massive systems miss the design intent and, to a great extent, nearly every benefit of using UNIX over VAX.

This excludes many of the operating systems licensed to use the trademark "UNIX." In this regard, even though Plan 9 is obviously not UNIX, it's a lot closer to it than (any) Linux and FreeBSD.

[skissane]

> Massive systems miss the design intent and, to a great extent, nearly every benefit of using UNIX over VAX

I take it you meant to say "VMS" here, not VAX.

I don't think the size of a system is essential to whether it counts as "UNIX" or not. The normal trajectory of any system which starts small is to progressively grow bigger, as demands and use cases and person-years invested all accumulate. UNIX has followed exactly that trajectory. I don't see why if a small system gradually grows bigger it at some point stops being itself.

I think there are three main senses of UNIX – "trademark UNIX" (passing the conformance test suite and licensing the trademark from the Open Group), "heritage/genealogical UNIX" (being descended from the original Bell Labs Unix code base), "Unix-like" (systems like Linux which don't descend from Bell Labs code and, with rare exception, don't formally pass the test suite and license the trademark, but which still aim at a very high degree of Unix compatibility). I think all three senses are valid, and I don't think size or scale is an essential component of any of them.

UNIX began life on small machines (PDP-7 then PDP-11), but was before long ported to some very large ones (for their day) – such as IBM mainframes – and the operating system tends to grow to match the scale of the environment it is running in. AT&T's early 1980s IBM mainframe port [0] was noticeably complicated, being written as a layer on top of the pre-existing (and obscure) IBM mainframe operating system TSS/370. If being small is essential to being UNIX, UNIX was only a little more than 10 years old before it was already starting to grow out of being itself.

[0] https://www.bell-labs.com/usr/dmr/www/otherports/ibm.pdf

[caslon]

> I take it you meant to say "VMS" here, not VAX.

Embarrassing slip in this context (I was just reading the CLE spec, too!), but yes.

> UNIX has followed exactly that trajectory. I don't see why if a small system gradually grows bigger it at some point stops being itself.

Adding onto something (and tearing down the principles it was created on, as Linux and most modern BSDs do) doesn't always preserve the initial thing; a well-built house is better as itself than reworked into a McMansion. Moissanite isn't diamond; it's actually quite different.

An operating system that has a kernel with more lines of code than the entirety of v7 (including user programs) is too much larger than UNIX, and too much of the structure has been changed, to count as UNIX in any meaningful sense of the word.

> If being small is essential to being UNIX, UNIX was only a little more than 10 years old before it was already starting to grow out of being itself.

Correct, which is why many of the initial UNIX contributors started work on Plan 9.

[skissane]

You started out by saying:

> the only real UNIX systems available these days are illumos and xv6

And then when I ask you what makes those "real UNIX systems" you say:

> I'd say it's easiest to define what isn't: massive systems.

But I don't see how illumos doesn't count as a "massive system". Think of all the features included in illumos and its various distributions: two networking APIs (STREAMS and sockets), DTrace, ZFS, SMF, Contracts, Doors, zones, KVM, projects, NFS, NIS, iSCSI, NSS, PAM, Crossbow, X11, Gnome, IPS (or pkgsrc on SmartOS), the list just goes. illumos strictly speaking is just the kernel, and while much of the preceding is in the kernel, some of it is user space only; but, to really do an apples-to-apples comparison, we have to include the user space (OpenIndiana, SmartOS, whatever) as well. Solaris and its descendant illumos are just as massive systems as Linux or *BSD or AIX or macOS are.

I will grant you that xv6 is not a massive system. But xv6 was designed for use in operating systems education, not for production use (whether as a workstation or server). If you actually tried to use xv6 for production purposes, you'd soon enough add so much stuff to it, that it would turn into just as massive a system as any of these are.

[caslon]

> Think of all the features included in illumos and its various distributions: two networking APIs (STREAMS and sockets), DTrace, ZFS, SMF, Contracts, Doors, zones, KVM, projects, NFS, NIS, iSCSI, NSS, PAM, Crossbow, X11, Gnome, IPS (or pkgsrc on SmartOS), the list just goes.

Much of what you mention isn't actually necessary/isn't actually in every distribution! Including X11 and GNOME as a piece of it is a bit extreme, don't you think? I also think it's a bit extreme to put things that are obviously mistakes (Zones, doors, SMF, IPS) in with things that actually simplify the system (DTrace and ZFS, most importantly) as reasons for why illumos is overly-complex.

I mostly agree with the idea that we have to include user space; even then, it's still clear that illumos is much closer to sane, UNIX-ideals than Linux is. I'm not going to claim that the illumos libc is perfect (far from it!), but the difference in approach between it and glibc highlights how deep the divide runs here. illumos, including its userspace, is significantly smaller than most Linux, massively smaller than macOS, slightly smaller than FreeBSD (and much better designed). All of these, though, are of course much smaller and far more elegant than AIX, so in that way we all win.

I don't actually know much more I would add to xv6. If anything, I'd start by removing things. Mainly, I hate fork. Of course, its userspace is relatively small, but v7's userspace is more or less enough for me (anecdotally, I spend much of my time within via SIMH and it's pretty comfortable, although there are obviously limits to this), so it wouldn't take many more additions to make it a comfortable environment.

Again, I'm not claiming Linux is bad (I love Linux!), simply that it isn't UNIX and doesn't adhere to the UNIX philosophy.