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

[Alejandro Colomar <alx@kernel.org>]

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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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