[TUHS] Pipes (was Re: After 50 years, what has the Impact of Unix been?)

[Heinz Lycklama]

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 at taugh.com, Taughannock Networks, Trumansburg NY
> Please consider the environment before reading this e-mail. https://jl.ly
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