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

[John R Levine]

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