[TUHS] etymology of read -u

[TUHS] etymology of read -u

[Doug McIlroy]

What's the mnmonic significance, if any, of the u in
the bash builtin read -u for reading from a specified
file descriptor? Evidently both f and d had already been
taken in analogy to usage in some other commands.

The best I can think of is u as in "tape unit", which
was common usage back in the days of READ INPUT TAPE 5.
That would make it the work of an old timer, maybe Dave Korn?

[TUHS] etymology of read -u

[Chet Ramey]

On 5/31/16 3:27 AM, Doug McIlroy wrote:
> What's the mnmonic significance, if any, of the u in
> the bash builtin read -u for reading from a specified
> file descriptor? Evidently both f and d had already been
> taken in analogy to usage in some other commands.
> 
> The best I can think of is u as in "tape unit", which
> was common usage back in the days of READ INPUT TAPE 5.
> That would make it the work of an old timer, maybe Dave Korn?

I picked it up from ksh many years ago, and assumed at the time that it
meant `unit'.

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
		 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    chet at case.edu    http://cnswww.cns.cwru.edu/~chet/

[TUHS] etymology of read -u

[Joerg Schilling]

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Doug McIlroy <doug at cs.dartmouth.edu> wrote:

> What's the mnmonic significance, if any, of the u in
> the bash builtin read -u for reading from a specified
> file descriptor? Evidently both f and d had already been
> taken in analogy to usage in some other commands.

It seems to be a copy from ksh.

Ksh implements a private "print" builtin that also uses -u fd.

Jörg

-- 
 EMail:joerg at schily.net                  (home) Jörg Schilling D-13353 Berlin
       joerg.schilling at fokus.fraunhofer.de (work) Blog: http://schily.blogspot.com/
 URL:  http://cdrecord.org/private/ http://sourceforge.net/projects/schilytools/files/'

[TUHS] etymology of read -u

[Dan Cross]

I asked Jeff Korn (David Korn's son), who in turn asked David Korn who
confirmed that 'read -u' comes from ksh and that 'u' stands for 'unit'.

        - Dan C.
Yes, indeed. He says:

*I added -u when I added co processes in the mid '80s.  The u stands for
unit.  It was command to talk about file descriptor unit at that time.*

On Tue, May 31, 2016 at 6:06 AM, Dan Cross <crossd at gmail.com> wrote:

> Hey, did your dad do `read -u`?
>
> ---------- Forwarded message ----------
> From: Doug McIlroy <doug at cs.dartmouth.edu>
> Date: Tue, May 31, 2016 at 3:27 AM
> Subject: [TUHS] etymology of read -u
> To: tuhs at minnie.tuhs.org
>
>
> What's the mnmonic significance, if any, of the u in
> the bash builtin read -u for reading from a specified
> file descriptor? Evidently both f and d had already been
> taken in analogy to usage in some other commands.
>
> The best I can think of is u as in "tape unit", which
> was common usage back in the days of READ INPUT TAPE 5.
> That would make it the work of an old timer, maybe Dave Korn?
>
>
>
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[TUHS] etymology of read -u

[Joerg Schilling]

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Dan Cross <crossd at gmail.com> wrote:

> I asked Jeff Korn (David Korn's son), who in turn asked David Korn who
> confirmed that 'read -u' comes from ksh and that 'u' stands for 'unit'.

Thank you for your reply....

Is this "the method" ;-) to get a reply from David since he works at Google?

Jörg

-- 
 EMail:joerg at schily.net                  (home) Jörg Schilling D-13353 Berlin
       joerg.schilling at fokus.fraunhofer.de (work) Blog: http://schily.blogspot.com/
 URL:  http://cdrecord.org/private/ http://sourceforge.net/projects/schilytools/files/'

[TUHS] etymology of read -u

[Doug McIlroy]

> I asked Jeff Korn
There's nothing like primary sources. Thanks, Dan.

Doug

[TUHS] etymology of read -u

[Doug McIlroy]

> I asked Jeff Korn 
There's nothing like primary sources. Thanks, Dan.

doug