Chronological order of BSD, SV, and POSIX.1

Chronological order of BSD, SV, and POSIX.1

[Seth McDonald]

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Hi Alex,

In my next patch set (for system calls), I've generally been ordering
POSIX.1-1988/1990 relative to BSD and SV according to their release
years as specified in standards(7).  Which gives the following relative
ordering between SV and POSIX.1:

SVr1
SVr2
SVr3
	POSIX.1-1988
SVr4
	POSIX.1-1990
SVID 4

And the following relative ordering between BSD and POSIX.1:

3BSD
4BSD
4.1BSD
4.2BSD
4.3BSD
	POSIX.1-1988
	POSIX.1-1990
4.4BSD

Because many of the system calls I updated listed SVr4, and some listed
4.4BSD, I want to check that it makes sense to list them after
POSIX.1-1988.  In case, for example, SVr4 is known to have influenced
POSIX.1-1988 prior to being officially released.

(I've also taken your recommendation and am trying out mutt(1), starting
with this email.  It's certainly a learning curve, but I'm slowly
getting there!)

-- 
Take care,
	Seth McDonald.

<sethmcmail at pm dot me> (on-list)
2336 E8D2 FEB1 5300 692C  62A9 5839 6AD8 9243 D369

<mcdonald_seth at pm dot me> (off-list)
82B9 620E 53D0 A1AE 2D69  6111 C267 B002 0A90 0289


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Re: Chronological order of BSD, SV, and POSIX.1

[Alejandro Colomar]

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[CC += наб, Branden]

On Sat, Jan 17, 2026 at 10:37:36AM +0000, Seth McDonald wrote:
> Hi Alex,

Hi Seth, наб,

> In my next patch set (for system calls), I've generally been ordering
> POSIX.1-1988/1990 relative to BSD and SV according to their release
> years as specified in standards(7).  Which gives the following relative
> ordering between SV and POSIX.1:
> 
> SVr1
> SVr2
> SVr3
> 	POSIX.1-1988
> SVr4
> 	POSIX.1-1990
> SVID 4
> 
> And the following relative ordering between BSD and POSIX.1:
> 
> 3BSD
> 4BSD
> 4.1BSD
> 4.2BSD
> 4.3BSD
> 	POSIX.1-1988
> 	POSIX.1-1990
> 4.4BSD

That seems to match standards(7).

There are more SV standards than those documented in standards.  I think
we should document these in standards(7):

SVID Issue 2 (1986):
<https://bitsavers.org/pdf/att/unix/SVID/System_V_Interface_Definition_Issue_2_Volume_1_1986.pdf>

SVID Issue 3 (1991):
<https://archive.org/details/systemvinterface0001unse>

I wonder how these influenced early POSIX and ANSI C.  I know that some
SVID heavily influenced ANSI C, at least regarding allocation functions.
<https://nabijaczleweli.xyz/content/blogn_t/017-malloc0.html>

Also, I suspect SVID eventually was absorbed by POSIX.  POSIX.1-2001 is
known as "Issue 6", and it sometimes refers to earlier issues, and I
don't know if some of those issues refer to SVID or early POSIX
versions.  It would be good to document that under standards(7) if we
learn it.

> Because many of the system calls I updated listed SVr4, and some listed
> 4.4BSD, I want to check that it makes sense to list them after
> POSIX.1-1988.  In case, for example, SVr4 is known to have influenced
> POSIX.1-1988 prior to being officially released.

I don't know much of this.  I've CCed наб, who I suspect will be able
to confirm much of this, and fill the gaps.  Also Branden might know
since he's subscribed to the TUHS mailing list.  (You may find TUHS
interesting, if you're into old standards.  See <https://www.tuhs.org/>.)

наб, would you mind having a look at standards(7) and fill the gaps?
Links to standards would also be very useful!  :-)

> (I've also taken your recommendation and am trying out mutt(1), starting
> with this email.  It's certainly a learning curve, but I'm slowly
> getting there!)

:)


Have a lovely day!
Alex

-- 
<https://www.alejandro-colomar.es>

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Re: Chronological order of BSD, SV, and POSIX.1

[Alejandro Colomar]

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[CC += linux-man]

Hi,

On Sat, Jan 17, 2026 at 10:05:30PM +0100, наб wrote:
> Not off-rip, and, as noted, I don't consider viewing the domain
> from this angle useful.
> 
> But, illustratively,
>   SUSv1 self-IDs as System Interface Definitions Issue 4, Version 2
>   SUSv2 self-IDs as System Interface Definitions Issue 5
>   SUSv3 self-IDs as The Open Group Base Specifications Issue 6, IEEE Std 1003.1, 2004 Edition
> QED

Hmmm, and XPGv3 and XPGv4 are Issue 3 and 4.

So, SVID 3 forked away (now it makes sense why SVID 2 says "Issue 2" but
SVID 3 says "Third Edition"), and then possibly merged back later.  :)

I've applied some small patches:

	commit f17241696722c472c5fcd06ee3b7af7afc3f1082
	Author: Alejandro Colomar <alx@kernel.org>
	Date:   Sun Jan 18 02:12:29 2026 +0100

	    man/man7/standards.7: XPGv3 and XPGv4 were Issue 3 and Issue 4
	    
	    Cc: наб <nabijaczleweli@nabijaczleweli.xyz>
	    Cc: Seth McDonald <sethmcmail@pm.me>
	    Signed-off-by: Alejandro Colomar <alx@kernel.org>

	diff --git a/man/man7/standards.7 b/man/man7/standards.7
	index ad244067f..7f1ad3ca4 100644
	--- a/man/man7/standards.7
	+++ b/man/man7/standards.7
	@@ -295,11 +295,15 @@ .SS POSIX and SUS
	 .B XPG3
	 Released in 1989, this was the first release of the X/Open
	 Portability Guide to be based on a POSIX standard (POSIX.1-1988).
	+It is also known as
	+.IR Issue\~3 .
	 This multivolume guide was developed by the X/Open Group,
	 a multivendor consortium.
	 .TP
	 .B XPG4
	 A revision of the X/Open Portability Guide, released in 1992.
	+It is also known as
	+.IR Issue\~4 .
	 This revision incorporated POSIX.2.
	 .TP
	 .B XPG4v2

	commit f15e61d56be7b7799f31e667aad61b10a3d64f75
	Author: Alejandro Colomar <alx@kernel.org>
	Date:   Sun Jan 18 02:08:06 2026 +0100

	    man/man7/standards.7: Fix names of SVID revisions, and add links
	    
	    Cc: наб <nabijaczleweli@nabijaczleweli.xyz>
	    Cc: Seth McDonald <sethmcmail@pm.me>
	    Signed-off-by: Alejandro Colomar <alx@kernel.org>

	diff --git a/man/man7/standards.7 b/man/man7/standards.7
	index 19a7f12b2..ad244067f 100644
	--- a/man/man7/standards.7
	+++ b/man/man7/standards.7
	@@ -75,15 +75,17 @@ .SS Unix/TS
	 .B System V release 2 (SVr2)
	 This was the next System V release, made in 1985.
	 The SVr2 was formally described in the
	-.I "System V Interface Definition version 1"
	+.I "System V Interface Definition Issue 1"
	 .RI ( "SVID 1" )
	 published in 1985.
	 .TP
	 .B System V release 3 (SVr3)
	 This was the successor to SVr2, released in 1986.
	 This release was formally described in the
	-.I "System V Interface Definition version 2"
	-.RI ( "SVID 2" ).
	+.UR https://bitsavers.org/pdf/att/unix/SVID/System_V_Interface_Definition_Issue_2_Volume_1_1986.pdf
	+.I "System V Interface Definition Issue 2"
	+.RI ( "SVID 2" )
	+.UE .
	 .TP
	 .B System V release 4 (SVr4)
	 This was the successor to SVr3, released in 1989.
	@@ -91,8 +93,10 @@ .SS Unix/TS
	 Manual: Operating System API (Intel processors)" (Prentice-Hall
	 1992, ISBN 0-13-951294-2)
	 This release was formally described in the
	-.I "System V Interface Definition version 3"
	-.RI ( "SVID 3" ),
	+.UR https://archive.org/details/systemvinterface0001unse/
	+.I "System V Interface Definition Third Edition"
	+.RI ( "SVID 3" )
	+.UE ,
	 and is considered the definitive System V release.
	 .TP
	 .B SVID 4

	commit c7c2b4668a6b84994a2c14535ab22f9e841c3991
	Author: Alejandro Colomar <alx@kernel.org>
	Date:   Sun Jan 18 01:54:33 2026 +0100

	    man/man7/standards.7: SUSv2 is Issue 5
	    
	    Cc: наб <nabijaczleweli@nabijaczleweli.xyz>
	    Cc: Seth McDonald <sethmcmail@pm.me>
	    Signed-off-by: Alejandro Colomar <alx@kernel.org>

	diff --git a/man/man7/standards.7 b/man/man7/standards.7
	index 4b21df5a8..19a7f12b2 100644
	--- a/man/man7/standards.7
	+++ b/man/man7/standards.7
	@@ -315,8 +315,8 @@ .SS POSIX and SUS
	 .TP
	 .B SUSv2
	 Single UNIX Specification version 2.
	-Sometimes also referred to (incorrectly) as
	-.IR XPG5 .
	+Sometimes also referred to as
	+.IR Issue\~5 .
	 This standard appeared in 1997.
	 Systems conforming to this standard can be branded
	 .IR UNIX\~98 .

> > > Early POSIX.1 and .2 derived much of their wording from their
> > > respective antecedent documents and some sentences still blame back
> > > to the SysIII manual.
> > It would be good to document for example things like "this standard was
> > incorporated in that later standard", to have a rough idea of the
> > standard lineages.
> At a 10km POV "newer standards copy stuff from older standards",
> which is neither novel nor interesting to the reader,
> and at a precise POV this is book-sized.

The details of how these frobnicate themselves can be documented per
page if necessary, or omitted if unimportant.

But a 10 km (or 40 yr) overview is important to keep, because otherwise
when someone talks about the SVID or XPG, I have no clue of what they
are talking about.  I've recently learnt some of that lost history, most
of it thanks to you, but otherwise I'd be blind; and I'd like to make it
possible for others to also know what people are talking about when they
mention ancient standards or systems.

In my head, there's now a tree which looks more or less like this
(oversimplified, and maybe technically incorrect in some places):

	V1
	V2
	V3
	V4
	V5-- 1BSD					  /--- OpenBSD	
	V6-----\ 2BSD				 /------ NetBSD
	V7---------\ 3BSD - 4BSD - 4.3BSD Lite --
	|					 \------ FreeBSD
	SysIII
	Unix/TS 4
X3J11	SysVr1
|	SysVr2 => SVID Issue 1
|	SysVr3 => SVID Issue 2 ---------\
C89	SysVr4 => SVID 3rd Ed.	    	POSIX.1-1988 =========> XPG Issue 3
|		  SVID 4th Ed.	    	POSIX.1-1990,POSIX.2 => XPG Issue 4
C95					|			XPG Issue 4, v2 ======> SUSv1
|					POSIX.1-1996					|
|					|		/-------------------------------SUSv2 (Issue 5)
C99	- - - - - - - - - - - ->	|/-------------/						
|					POSIX.1-2001, SUSv3 (Issue 6)
|					POSIX.1-2008, SUSv4 (Issue 7)
C11					|
C17	- - - - - - - - - - - ->	POSIX.1-2024, SUSv5 (Issue 8)
C23

This tree is quite useful to me, even though they frobnicated a lot more
between them.  At least I now have a rough idea of the context each
standard had, and thus the possible frobnications.

I've CCed the list so that this tree is documented there.  It might be
useful.


Have a lovely night!
Alex

-- 
<https://www.alejandro-colomar.es>

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Re: Chronological order of BSD, SV, and POSIX.1

[G. Branden Robinson]

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Hi Alex,

At 2026-01-18T02:51:55+0100, Alejandro Colomar wrote:
> 	V1
> 	V2
> 	V3
> 	V4
> 	V5-- 1BSD					  /--- OpenBSD	
> 	V6-----\ 2BSD				 /------ NetBSD
> 	V7---------\ 3BSD - 4BSD - 4.3BSD Lite --

Let me offer some corrections here, drawn partially from McKusick's
article "20 Years of Berkeley Unix".[1]  Sorry it's gonna make the lines
longer.

	V5-- 1BSD
	V6-----\ 2BSD ---- 2.8BSD ------ 2.11BSD		/--- OpenBSD
	V7	    \	  /		/		    /------ NetBSD
	32/V---------\ 3BSD - 4BSD - 4.3BSD - 4.4BSD-Lite --
	|						    \------ FreeBSD
	SysIII
	Unix/TS 4

The salient points being:

* Unix 32/V, being the port to the DEC VAX, was a huge deal and
  ultimately the common ancestor of _all_ AT&T and BSD Unices.  I won't
  say nobody ever developed Unix on any 16-bit platform besides the
  PDP-11 ever again, but I venture that any such efforts are now mostly
  obscure, and not impactful on the C or POSIX standards.  ("near" and
  "far" did not make it into ANSI C, for example, and if the x86
  couldn't manage that, no other chip was going to.)

* 2BSD, being a PDP-11-only product, kept the PDP-11 Unix kernel but
  refreshed its userspace from the {3,4}BSD mothership on an ongoing
  basis, where memory constraints permitted, and indeed 2.11BSD
  continues to be developed as of 2025^Wwhoops, scratch that, patch #499
  came out 3 days ago.[1]

* There was no 4.3BSD-Lite.  4.4BSD-Lite is what you mean.  Strictly,
  "4.4BSD-Lite Release 2" was the end of the road, after which the CSRG
  disbanded and several of its principals departed to BSDI where
  unimaginable riches awaited them.  Surely.

* Despite the previous, it's good to have 4.3BSD on the chart because it
  endured a very long time.  (To some frustration at the CSRG, but as I
  understand it, AT&T Corporate spent years making ever louder threats
  that they were going to sue the bejeezus out of Berkeley so that BSD
  Unix, which was so aggravatingly popular with all the cheap computer
  science labor spewing from the universities, quit creating headaches
  for its marketers and price-fixers.)  4.3BSD was so influential that
  much of it got folded back into SVr4, around the same time Sun
  Microsystems sold its soul (and a major stake of equity) to AT&T.

Regards,
Branden

[1] https://www.oreilly.com/openbook/opensources/book/kirkmck.html
[2] https://minnie.tuhs.org/TUHS/Archive/Distributions/UCB/2.11BSD/Patches/

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Re: Chronological order of BSD, SV, and POSIX.1

[Alejandro Colomar]

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Hi Branden,

On Sat, Jan 17, 2026 at 08:33:23PM -0600, G. Branden Robinson wrote:
> Hi Alex,
> 
> At 2026-01-18T02:51:55+0100, Alejandro Colomar wrote:
> > 	V1
> > 	V2
> > 	V3
> > 	V4
> > 	V5-- 1BSD					  /--- OpenBSD	
> > 	V6-----\ 2BSD				 /------ NetBSD
> > 	V7---------\ 3BSD - 4BSD - 4.3BSD Lite --
> 
> Let me offer some corrections here, drawn partially from McKusick's
> article "20 Years of Berkeley Unix".[1]  Sorry it's gonna make the lines
> longer.
> 
> 	V5-- 1BSD
> 	V6-----\ 2BSD ---- 2.8BSD ------ 2.11BSD		/--- OpenBSD
> 	V7	    \	  /		/		    /------ NetBSD
> 	32/V---------\ 3BSD - 4BSD - 4.3BSD - 4.4BSD-Lite --
> 	|						    \------ FreeBSD
> 	SysIII
> 	Unix/TS 4

Thanks!!

> The salient points being:
> 
> * Unix 32/V, being the port to the DEC VAX, was a huge deal and
>   ultimately the common ancestor of _all_ AT&T and BSD Unices.  I won't
>   say nobody ever developed Unix on any 16-bit platform besides the
>   PDP-11 ever again, but I venture that any such efforts are now mostly
>   obscure, and not impactful on the C or POSIX standards.  ("near" and
>   "far" did not make it into ANSI C, for example, and if the x86
>   couldn't manage that, no other chip was going to.)
> 
> * 2BSD, being a PDP-11-only product, kept the PDP-11 Unix kernel but
>   refreshed its userspace from the {3,4}BSD mothership on an ongoing
>   basis, where memory constraints permitted, and indeed 2.11BSD
>   continues to be developed as of 2025^Wwhoops, scratch that, patch #499
>   came out 3 days ago.[1]
> 
> * There was no 4.3BSD-Lite.  4.4BSD-Lite is what you mean.

Yup; accident.

>   Strictly,
>   "4.4BSD-Lite Release 2" was the end of the road, after which the CSRG
>   disbanded and several of its principals departed to BSDI where
>   unimaginable riches awaited them.  Surely.
> 
> * Despite the previous, it's good to have 4.3BSD on the chart because it
>   endured a very long time.  (To some frustration at the CSRG, but as I
>   understand it, AT&T Corporate spent years making ever louder threats
>   that they were going to sue the bejeezus out of Berkeley so that BSD
>   Unix, which was so aggravatingly popular with all the cheap computer
>   science labor spewing from the universities, quit creating headaches
>   for its marketers and price-fixers.)  4.3BSD was so influential that
>   much of it got folded back into SVr4, around the same time Sun
>   Microsystems sold its soul (and a major stake of equity) to AT&T.
>
> Regards,
> Branden
> 
> [1] https://www.oreilly.com/openbook/opensources/book/kirkmck.html
> [2] https://minnie.tuhs.org/TUHS/Archive/Distributions/UCB/2.11BSD/Patches/

Very interesting; thanks!


Have a lovely day!
Alex

-- 
<https://www.alejandro-colomar.es>

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Re: Chronological order of BSD, SV, and POSIX.1

[Alejandro Colomar]

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Hi Seth,

On Sat, Jan 17, 2026 at 10:37:36AM +0000, Seth McDonald wrote:
> Hi Alex,
> 
> In my next patch set (for system calls), I've generally been ordering
> POSIX.1-1988/1990 relative to BSD and SV according to their release
> years as specified in standards(7).  Which gives the following relative
> ordering between SV and POSIX.1:
> 
> SVr1
> SVr2
> SVr3
> 	POSIX.1-1988
> SVr4
> 	POSIX.1-1990
> SVID 4
> 
> And the following relative ordering between BSD and POSIX.1:
> 
> 3BSD
> 4BSD
> 4.1BSD
> 4.2BSD
> 4.3BSD
> 	POSIX.1-1988
> 	POSIX.1-1990
> 4.4BSD
> 
> Because many of the system calls I updated listed SVr4, and some listed
> 4.4BSD, I want to check that it makes sense to list them after
> POSIX.1-1988.  In case, for example, SVr4 is known to have influenced
> POSIX.1-1988 prior to being officially released.

Going back to this, yes, 4.4BSD seems clearly later than POSIX.1-1990.

SVr4 seems contemporaneous to POSIX.1-1988, so I don't mind whether we
put it before or after.  I think I'd put it before, because as you say,
it heavily influenced, even though formally POSIX.1-1988 seems to
derive from SVr3 (SVID Issue 2).  That also puts all SysV before all
POSIX, which seems cleaner.

Let's try to specify the order in the format you used above:

3BSD
4BSD
4.1BSD
	SysIII
	Unix/TS 4
4.2BSD
	SVr1
	SVr2
4.3BSD
	SVr3
	SVr4
					C89
		POSIX.1-1988
				XPG3
		POSIX.1-1990
				XPG4
				SUSv1
	SVID 4
4.4BSD
					C95
		POSIX.1-1996
				SUSv2
					C99
		POSIX.1-2001	SUSv3
		POSIX.1-2008	SUSv4
					C11
					C17
		POSIX.1-2024	SUSv5
					C23


Have a lovely day!
Alex

-- 
<https://www.alejandro-colomar.es>

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