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John, thanks for the reminder of the implementation<br>
of pipes on a constrained version of UNIX in the early<br>
days. The exact implementation is described on page 2095<br>
of the BSTJ July-Aug 1978 for interested parties.<br>
<br>
<img src="cid:part1.8olMNqGV.nBBEN64f@osta.com" alt="" width="700"
height="196"><br>
<br>
Heinz<br>
<br>
<div class="moz-cite-prefix">On 12/5/2024 8:00 AM, John R Levine
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:32bf4263-277d-8c8b-6bf7-e33df04a2c3c@taugh.com">On Thu,
5 Dec 2024, Dan Cross wrote:
<br>
<blockquote type="cite">
<blockquote type="cite">Pipes were invented at least three times
I'm aware of, but what made them
<br>
work so well in Unix is that they looked to the program the
same as a file
<br>
so any program could use them for input or output without
special arrangements,
<br>
and the shell made it easy to start two programs and pipe them
together.
<br>
</blockquote>
<br>
Once you have coroutines and queues for passing data between
them, a
<br>
lot of things start to look like pipes.
<br>
</blockquote>
<br>
They also can look a lot like temporary files. Someone, probably
Heinz, did a shell for the tiny Unix that ran on floppies so this
<br>
<br>
foo | bar
<br>
<br>
actually did this
<br>
<br>
foo > tmpfile ; bar < tmpfile; rm tmpfile
<br>
<br>
to avoid having to swap programs in and out on floppies. The main
disadvantage was that the tmpfile could overflow the tiny disks of
the time.
<br>
<br>
<blockquote type="cite">
<blockquote type="cite">They were invented again at IBM in the
1970s and described in this paper. I wrote
<br>
them a letter, which they published, saying that Unix pipes
did the same thing.
<br>
<br>
<a class="moz-txt-link-freetext" href="https://dl.acm.org/doi/10.1147/sj.174.0383">https://dl.acm.org/doi/10.1147/sj.174.0383</a>
<br>
</blockquote>
<br>
Don't forget CMS pipelines, too!
<br>
<br>
Sadly, the Morrison paper cited above is not easily accessible,
though
<br>
</blockquote>
<br>
If anyone else needs a copy, just ask.
<br>
<br>
Regards,
<br>
John Levine, <a class="moz-txt-link-abbreviated" href="mailto:johnl@taugh.com">johnl@taugh.com</a>, Taughannock Networks, Trumansburg NY
<br>
Please consider the environment before reading this e-mail.
<a class="moz-txt-link-freetext" href="https://jl.ly">https://jl.ly</a>
<br>
</blockquote>
<br>
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