[TUHS] Pipes in the Third Edition Unix

[Clem Cole]

Hmm.. it's all about where you count.   Clearly, he was working on it if
the stubs is there.  If the only difference between 3rd and 4th is the pipe
code, then it would be fair to say that.

You might say something like:  Pipe's were developed in a 3rd edition
kernel, where there was is evidence of nascent idea (its has a name and
there are subs for it), but the code to fully support it is lacking in the
3rd release.  Pipes became a completed feature in the 4th edition.

On Tue, Jan 3, 2017 at 3:54 PM, Diomidis Spinellis <dds at aueb.gr> wrote:

> Peter Salus writes "The other innovation present in the Third Edition was
> the pipe" ("A Quarter Century of Unix", p. 50).  Yet, in the corresponding
> sys/ken/sysent.c, the pipe system call seems to be a stump.
>
>         1, &fpe,                        /* 40 = fpe */
>         0, &dup,                        /* 41 = dup */
>         0, &nosys,                      /* 42 = pipe */
>         1, &times,                      /* 43 = times */
>
> On the other hand, the Fourth Edition manual documents the pipe system
> call, the construction of pipelines through the shell, and the use of wc as
> a filter (without an input file, as was required in the Second Edition).
>
> Would it therefore be correct to say that pipes were introduced in the
> Fourth rather than the Third Edition?
>
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