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From: Warner Losh <imp@bsdimp.com>
To: Clem Cole <clemc@ccc.com>
Cc: The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: [TUHS] Re: FD 2
Date: Sat, 21 Jan 2023 10:50:17 -0700	[thread overview]
Message-ID: <CANCZdfr4zkmFKgqBZKrOL9z5FbFsWSjHpU3vYu-2T3Y+xNat2g@mail.gmail.com> (raw)
In-Reply-To: <CANCZdfpjrJUDPv2g7-10SrdkgjiacAvp95PVvJ=Ob2h8m8R=FQ@mail.gmail.com>

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On Sat, Jan 21, 2023, 10:34 AM Warner Losh <imp@bsdimp.com> wrote:

>
>
> On Sat, Jan 21, 2023, 8:45 AM Clem Cole <clemc@ccc.com> wrote:
>
>> Certainly fd 2 as a error output appears with Lesk's portable C library,
>> which was included in V6 - see the last para on page 1 of his document:
>>
>> "Initially you are given three file descriptors by the system: 0, 1, and
>> 2. File 0 is the standard input; it is normally the teletype in
>> time-sharing or input data cards in batch. File 1 is the standard output;
>> it is nor- mally the teletype in time-sharing or the line printer in batch.
>> File 2 is the error file; it is an output file, nor- mally the same as file
>> 1, except that when file 1 is diverted via a command line ’>’ operator,
>> file 2 remains attached to the original destination, usually the terminal.
>> It is used for error message output. These popular UNIX conventions are
>> considered part of the C library specification. By closing 0 or 1, the
>> default input or output may be re-directed; this can also be done on the
>> command line by >file for output or <file for input."
>>
>> This document pre-dates ditroff.   The idea/names of stdin/out/err (as
>> opposed to fd 0, 1, 2) does not come about until Dennis does "typesetter C"
>> which is described in K&R.
>>
>> That said, my memory is fd 2 as ana error path was there in Fourth or
>> Fifth Edition, before Lesk did this library -- i.e. it was a convention
>> that Dennis/Ken et al were all using -- when it is realized that printing
>> errors on in the same output flow as the standard (normal) output was
>> problematic in a pipe stream.
>> ᐧ
>>
>
> It looks to be a mixed bag in 5th edition. Cc, ac, comm and find all
> printf the errors. Diff uses writes to fd 2. I didn't catalog further, but
> this kinda looks like a developing convention, not yet fully realized. .
>

Further digging shows v6 is quite similar. V7 revamps everything, with
printf changed to a routine that writes to stderr. Each program did this
differently.

Granted, this is a small sample size. There wasn't a huge uptake of
stderr/fd2 in v6 it seems, but v7 looks like it had a pass over the code to
at least try for all errors going to fd2.

Warner


> Warner
>
> On Fri, Jan 20, 2023 at 5:46 PM ron minnich <rminnich@gmail.com> wrote:
>>
>>> I am trying to remember when fd 2 (aka stderr) became a thing. I have a
>>> vague memory that it was post-v6 but that may be way off.
>>>
>>>
>>>

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  reply	other threads:[~2023-01-21 17:52 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-20 22:44 [TUHS] " ron minnich
2023-01-20 22:54 ` [TUHS] " G. Branden Robinson
2023-01-20 22:56 ` Rob Pike
2023-01-20 23:11   ` Larry McVoy
2023-01-20 23:14     ` Rob Pike
2023-01-20 23:22       ` Larry McVoy
2023-01-20 23:13 ` Douglas McIlroy
2023-01-21  3:37 ` Jon Steinhart
2023-01-21 15:42 ` Clem Cole
2023-01-21 17:34   ` Warner Losh
2023-01-21 17:50     ` Warner Losh [this message]
2023-01-21 18:26       ` Clem Cole
2023-01-21 18:37         ` Warner Losh
2023-01-22 11:05           ` Jonathan Gray
2023-01-22 21:23           ` Warner Losh
2023-01-22 22:10             ` ron minnich
2023-01-23  7:30             ` arnold
2023-01-23  8:32               ` James Johnston
2023-01-23  8:58                 ` G. Branden Robinson
2023-01-23 11:49                   ` Brantley Coile
2023-01-23 14:25                     ` Ronald Natalie
2023-01-23 17:43                       ` Brantley Coile
2023-01-23 16:59                 ` Douglas McIlroy
2023-01-24  7:21                   ` arnold
2023-01-29 18:51             ` Warner Losh
2023-01-29 19:20               ` Ron Natalie
2023-01-29 20:25                 ` Warner Losh
2023-01-30  7:50                   ` arnold
2023-01-30  8:09                     ` Rob Pike
2023-01-30 15:02                       ` Larry McVoy
2023-01-30 15:16                         ` Dan Cross
2023-01-30 15:27                           ` Larry McVoy
2023-01-30 15:35                             ` Dan Cross
2023-01-30 15:45                               ` Larry McVoy
2023-01-30 16:09                                 ` Dan Cross
2023-01-30 16:18                                   ` Larry McVoy
2023-01-30 19:03                                     ` Dan Cross
2023-01-30 19:12                                       ` Brantley Coile
2023-01-30 21:24                                       ` Larry McVoy
2023-01-30 22:15                                         ` Rob Pike
2023-01-30 22:50                                           ` ron minnich
2023-01-30 23:05                                           ` [TUHS] Child of plan9? (Re: " Bakul Shah
2023-01-31  3:19                                             ` [TUHS] " Andrew Warkentin
2023-01-30 16:21                                   ` [TUHS] " Steve Nickolas
2023-01-30 16:27                                     ` Larry McVoy
2023-01-30 16:32                                       ` ron minnich
2023-01-30 16:40                                       ` Clem Cole
2023-01-30 19:55                                       ` Lawrence Stewart
2023-01-31 21:27                                     ` Dave Horsfall
2023-01-30 16:48                                   ` Theodore Ts'o
2023-01-30 16:57                                   ` Andy Kosela
2023-01-30 17:04                                     ` Warner Losh
2023-01-30 20:38                                       ` Theodore Ts'o
2023-01-30 21:01                                         ` Warner Losh
2023-01-30 21:10                                         ` Clem Cole
2023-01-30 16:03                           ` Bakul Shah
2023-01-30 16:07                             ` Larry McVoy
2023-01-30 16:13                               ` Bakul Shah
2023-01-30 16:22                                 ` Steve Nickolas
2023-01-30 16:17                               ` Dan Cross
2023-01-30 16:18                             ` Ralph Corderoy
2023-01-30 16:41                               ` [TUHS] job control (Re: " Bakul Shah
2023-01-30 19:07                               ` [TUHS] " Dan Cross
2023-01-30 13:26                     ` John Cowan
2023-01-30 14:30                       ` arnold
2023-01-30  0:25                 ` Phil Budne
2023-01-30  2:08                   ` Warner Losh
2023-01-21 18:27     ` Clem Cole
2023-01-22 10:56       ` Jaap Akkerhuis via TUHS

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