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

[John Levine]

It appears that Marc Rochkind <mrochkind at gmail.com> said:
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>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. ...

You should read Meinz' paper.  This was a cut down version of Unix that ran
in 40K bytes on an LSI-11 with a couple of floppy disks.  It ran one program
at a time, since swapping to floppies was absurdly slow.  The pseudo-pipe
ran the first program which wrote the output to a file, then ran the second
program which read it.  It was close enough for most purposes so long as
the disk didn't fill up.

>Still, the same sort of pseudo-pipes were in MS-DOS, and they were
>occasionally useful.

I can think of lots of places that had a way for one program to write a temporary
file that a subsequent one read.  For example, in OS/360 JCL you'd write (well, punch)
something like this for the object output of the Fortran compiler

//SYSLIN DD DSNAME=&OBJECT,DISP=(NEW,PASS),UNIT=SYSSQ

and then in the linker read it in

//SYSIN DD DSNAME=&OBJECT,DISP=(OLD,DELETE)

The & in the name said it was a temp file so make up a unique name.  I probably didn't
get the JCL exactly right since it's been about 50 years since I wrote any.

R's,
John