5 Dec
2024
5 Dec
'24
10 p.m.
On Thu, 5 Dec 2024, Dan Cross wrote:
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.
If anyone else needs a copy, just ask.
Regards,
John Levine, johnl(a)taugh.com, Taughannock Networks, Trumansburg NY
Please consider the environment before reading this e-mail. https://jl.ly
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 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