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* [TUHS] Groups origins
@ 2021-10-03 22:10 Norman Wilson
  2021-10-04 13:39 ` John P. Linderman
  0 siblings, 1 reply; 5+ messages in thread
From: Norman Wilson @ 2021-10-03 22:10 UTC (permalink / raw)
  To: tuhs

I can't speak to the evolution and use of specific
groups; I suspect it was all ad-hoc early on.

Groups appeared surprisingly late (given how familiar
they seem now): they don't show up in the manual
until the Sixth Edition.  Before that, chown took
only two arguments (filename and owner), and
permission modes had three bits fewer.

I forget how it came up, but the late Lee McMahon
once told me an amusing story about their origin:

Ken announced that he was adding groups.

Lee asked what they were for.

Ken replied with a shrug and `I dunno.'

Norman Wilson
Toronto ON

^ permalink raw reply	[flat|nested] 5+ messages in thread
* [TUHS] Groups origins
@ 2021-10-04  1:22 Norman Wilson
  0 siblings, 0 replies; 5+ messages in thread
From: Norman Wilson @ 2021-10-04  1:22 UTC (permalink / raw)
  To: tuhs

  Groups appeared surprisingly late (given how familiar
  they seem now): they don't show up in the manual
  until the Sixth Edition.

Mea culpa; read too hastily.  The change actually
came with the Fourth Edition, at the same time as
several other landmark system changes:
-- Time changing from a 32-bit count of 60Hz clock
ticks (which ran out so quickly that its epoch kept
moving) to the modern 32 bits of whole seconds, based
at 1970-01-01T00:00:00 GMT (which takes much longer
to run out, though the horizon is now visible).
-- The modern super-block.  In 4/e, the super-block
began at block 0, not 1 (so bootstrapping was rather
more complicated); the free list was a bitmap rather
than the later list of blocks containing lists of
free block numbers.
-- The super-block contained a bitmap of free
i-numbers too.  All told, the free block and free
i-node map made up a 1024-byte super-block.
-- I-numbers 1-40 were device files; the root
directory was i-number 41.  The only file-type
indication in the mode word was a single bit to
denote directory.

It was already clear that the lifetime of the
bitmaps was running out: the BUGS section says
two blocks isn't enough for the bitmaps for a
20-megabyte RP02.

Norman Wilson
Toronto ON

^ permalink raw reply	[flat|nested] 5+ messages in thread
* [TUHS] Groups origins
@ 2021-10-03 21:54 Will Senn
  2021-10-03 23:22 ` Warner Losh
  0 siblings, 1 reply; 5+ messages in thread
From: Will Senn @ 2021-10-03 21:54 UTC (permalink / raw)
  To: tuhs

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Hi all,

I was reading a recent thread, over on the FreeBSD forums about groups that quickly devolved into a discussion on the origin of the operator group:
https://forums.freebsd.org/threads/groups-overview.82303/

I thought y’all would be the best place to ask the questions that arose in me during my read of the thread. 

Here they are in no special order:

1. Where did operator come from and what was it intended to solve?
2. How has it evolved.
3. What’s a good place to look/ref to read about groups, generally?

I liked one respondent’s answer about using find, heir, and the files themselves to learn about groups being used in a running system, paying attention to the owner, Audi, etc along the way and this is how I do it now, but this approach doesn’t account for the history and evolution.

Thanks!

Willu



Sent from my iPhone

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^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2021-10-04 13:41 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-10-03 22:10 [TUHS] Groups origins Norman Wilson
2021-10-04 13:39 ` John P. Linderman
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2021-10-04  1:22 Norman Wilson
2021-10-03 21:54 Will Senn
2021-10-03 23:22 ` Warner Losh

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