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From: John Cowan <cowan@ccil.org>
To: Marc Rochkind <mrochkind@gmail.com>
Cc: The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: [TUHS] Re: Pipes (was Re: After 50 years, what has the Impact of Unix been?)
Date: Thu, 5 Dec 2024 12:53:06 -0500	[thread overview]
Message-ID: <CAD2gp_SUWyBukKki6boxq5m4ebCgwD97dyeMArCEmwOu6vJ14g@mail.gmail.com> (raw)
In-Reply-To: <CAOkr1zV7goW0H3WwtCquuTLCWs4m=aEp8HR0hnKUJMjkMH_Juw@mail.gmail.com>


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There was no concurrency in mini-Unix; the first pipeline component ran to
completion, and when it exited the next component ran, and so on.  In this
way a pipeline could be arbitrarily long using just two disk files.

On Thu, Dec 5, 2024, 12:07 PM Marc Rochkind <mrochkind@gmail.com> wrote:

> I don't think files as pipes would be "transparent to the user." Reading
> an empty pipe causes a wait until the bytes requested are available, unless
> the pipe is closed first. Reading to the end of a file results in an
> end-of-file error. This problem is avoided if the source process completes
> before the target process begins, but then there is a different lack of
> transparency, which is that the processes don't run simultaneously. (I
> think this is the case with the implementation that Heinz showed.)
>
> Still, the same sort of pseudo-pipes were in MS-DOS, and they were
> occasionally useful.
>
> Marc
>
> On Thu, Dec 5, 2024 at 9:17 AM Heinz Lycklama <heinz@osta.com> wrote:
>
>> John, thanks for the reminder of the implementation
>> of pipes on a constrained version of UNIX in the early
>> days. The exact implementation is described on page 2095
>> of the BSTJ July-Aug 1978 for interested parties.
>>
>>
>>
>> Heinz
>>
>> On 12/5/2024 8:00 AM, John R Levine wrote:
>>
>> On Thu, 5 Dec 2024, Dan Cross wrote:
>>
>> Pipes were invented at least three times I'm aware of, but what made them
>> work so well in Unix is that they looked to the program the same as a
>> file
>> so any program could use them for input or output without special
>> arrangements,
>> and the shell made it easy to start two programs and pipe them together.
>>
>>
>> Once you have coroutines and queues for passing data between them, a
>> lot of things start to look like pipes.
>>
>>
>> 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
>>
>>  foo | bar
>>
>> actually did this
>>
>>  foo > tmpfile ; bar < tmpfile; rm tmpfile
>>
>> 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.
>>
>> They were invented again at IBM in the 1970s and described in this
>> paper.  I wrote
>> them a letter, which they published, saying that Unix pipes did the same
>> thing.
>>
>> https://dl.acm.org/doi/10.1147/sj.174.0383
>>
>>
>> Don't forget CMS pipelines, too!
>>
>> Sadly, the Morrison paper cited above is not easily accessible, though
>>
>>
>> If anyone else needs a copy, just ask.
>>
>> Regards,
>> John Levine, johnl@taugh.com, Taughannock Networks, Trumansburg NY
>> Please consider the environment before reading this e-mail. https://jl.ly
>>
>>
>>
>
> --
> *My new email address is mrochkind@gmail.com <mrochkind@gmail.com>*
>

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  reply	other threads:[~2024-12-05 17:53 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-12-04  3:17 [TUHS] After 50 years, what has the Impact of Unix been? sjenkin
2024-12-04 13:05 ` [TUHS] " Marc Donner
2024-12-04 13:40   ` William Cheswick
2024-12-04 15:02   ` Rich Salz
2024-12-05  3:08   ` John Levine
2024-12-05 15:19     ` [TUHS] Re: Pipes (was Re: After 50 years, what has the Impact of Unix been?) Dan Cross
2024-12-05 16:00       ` John R Levine
2024-12-05 16:17         ` Heinz Lycklama
2024-12-05 17:06           ` Marc Rochkind
2024-12-05 17:53             ` John Cowan [this message]
2024-12-05 18:05             ` John Levine
2024-12-05 17:22           ` Paul Winalski
2024-12-05 18:19         ` Ron Natalie
2024-12-06  2:29           ` Adam Thornton
2024-12-07 20:38             ` Ron Natalie
2024-12-05 16:55       ` Adam Thornton
2024-12-05 17:35       ` Chet Ramey via TUHS
2024-12-05 20:55         ` arnold
2024-12-05 21:12           ` Dan Cross
2024-12-05 21:50             ` Marc Rochkind
2024-12-05 22:03             ` Warner Losh
2024-12-05 22:19               ` Chet Ramey via TUHS
2024-12-05 23:07                 ` Marc Rochkind
2024-12-06  8:16                   ` Diomidis Spinellis
2024-12-06  0:46                 ` Alexis
2024-12-06 21:46                   ` Chet Ramey via TUHS
2024-12-05 23:07               ` arnold
2024-12-06  1:09                 ` G. Branden Robinson
2024-12-06  1:31                   ` Greg A. Woods
2024-12-06  2:05                     ` Steve Nickolas
2024-12-06 16:44                     ` arnold
2024-12-05 22:05             ` Bakul Shah via TUHS
2024-12-06  2:02             ` John Levine
2024-12-06  2:21               ` Dan Cross
2024-12-06 16:46                 ` arnold
2024-12-06  2:26 Douglas McIlroy

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