From: lm@mcvoy.com (Larry McVoy)
Subject: [TUHS] UNIX of choice these days?
Date: Wed, 27 Sep 2017 07:17:06 -0700 [thread overview]
Message-ID: <20170927141706.GI28606@mcvoy.com> (raw)
In-Reply-To: <4e49a311-704d-6b70-92b3-27c6565f8aa0@case.edu>
On Wed, Sep 27, 2017 at 09:50:10AM -0400, Chet Ramey wrote:
> On 9/26/17 10:02 PM, Larry McVoy wrote:
>
> >>> Yeah, but still doesn't answer the question, application-wise.?? I'm gonna
> >>> guess (without digging through the source) that it's a "dup2(0, 255)*" or
> >>> something, to "save" a copy of stdin/out/err for some obscure reason.
> >>
> >> I already answered this.
> >
> > OK, I'm gonna be that guy because I've learned when I ask, I learn.
> >
> > You answered but I didn't get any insight. Why have an extra fd talking
> > to the tty? bash has 0, 1, 2 talking to it. If it were redirected
> > would it have 255 pointing to some random tty? I don't get the reason
> > for the extra fd.
>
> OK. The only way to guarantee you have a descriptor open to your
> controlling terminal is to open /dev/tty yourself. You can run `bash -im'
> and have yourself an interactive shell with job control enabled no matter
> where stdin/stdout/stderr point, and they can be redirected at any point
> during execution, so you can't count on them. But why do you have to have
> the fd in the first place?
All the tty stuff wasn't my question, I get all that, I did POSIX conformance
in SunOS, there was a time when I dreamed about setsid() et al :)
> ksh93 uses fd 2 no matter what, so you don't get job control if you
> redirect stderr away from the terminal.)
So that's the behaviour I'm used to (dating myself but this is TUHS so...)
My question really was why use an extra fd? If I run
bash something > /dev/null 2>&1
duh. ksh93 wouldn't let you ^Z that, eh? OK, makes sense, I hadn't
thought it through. Sorry for the brain fart.
next prev parent reply other threads:[~2017-09-27 14:17 UTC|newest]
Thread overview: 110+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-25 12:07 Norman Wilson
2017-09-25 14:16 ` Clem Cole
2017-09-25 15:13 ` Warner Losh
2017-09-25 16:51 ` Warner Losh
2017-09-26 0:56 ` ron minnich
2017-09-25 15:18 ` Larry McVoy
2017-09-25 15:30 ` Warner Losh
2017-09-25 23:49 ` Dave Horsfall
2017-09-26 2:06 ` Chet Ramey
2017-09-26 14:53 ` Larry McVoy
2017-09-26 15:17 ` Chet Ramey
2017-09-26 21:23 ` Dave Horsfall
2017-09-26 21:43 ` Arthur Krewat
2017-09-26 21:45 ` Grant Taylor
2017-09-27 0:58 ` Dave Horsfall
2017-09-27 1:37 ` Chet Ramey
2017-09-27 2:02 ` Larry McVoy
2017-09-27 13:50 ` Chet Ramey
2017-09-27 14:17 ` Larry McVoy [this message]
2017-09-28 8:10 ` Derek Fawcus
2017-09-28 12:34 ` Chet Ramey
[not found] ` <20170928174420.GA41732@accordion.employees.org>
2017-09-28 17:57 ` Derek Fawcus
2017-09-28 18:04 ` Chet Ramey
2017-09-27 3:42 ` Dave Horsfall
2017-09-27 14:35 ` Chet Ramey
-- strict thread matches above, loose matches on Subject: below --
2017-09-30 15:17 Norman Wilson
2017-09-30 20:29 ` Kevin Bowling
2017-09-30 21:56 ` Bakul Shah
2017-09-30 22:37 ` Kevin Bowling
2017-09-25 12:46 [TUHS] Unix " Doug McIlroy
2017-09-25 13:57 ` Clem Cole
2017-09-23 23:39 [TUHS] UNIX " Nelson H. F. Beebe
2017-09-21 2:28 Rudi Blom
2017-09-20 0:12 Arthur Krewat
2017-09-20 0:26 ` Larry McVoy
2017-09-20 0:39 ` Dave Horsfall
2017-09-20 1:03 ` Lyndon Nerenberg
2017-09-20 20:56 ` jason-tuhs
2017-09-23 9:17 ` Dario Niedermann
2017-09-23 9:36 ` Steve Mynott
2017-09-23 10:03 ` Dario Niedermann
2017-09-23 23:04 ` Dave Horsfall
2017-09-24 0:11 ` Random832
2017-09-24 1:19 ` Dave Horsfall
2017-09-24 13:46 ` Andy Kosela
2017-09-24 14:02 ` ron minnich
2017-09-24 14:06 ` Larry McVoy
2017-09-24 20:36 ` Kurt H Maier
2017-09-24 21:38 ` Bakul Shah
2017-09-24 23:36 ` Dave Horsfall
2017-09-24 23:50 ` Steve Nickolas
2017-09-25 0:03 ` Wesley Parish
2017-09-25 15:36 ` Tony Finch
2017-09-26 0:42 ` Wesley Parish
2017-09-26 9:54 ` Tony Finch
2017-09-26 14:41 ` Larry McVoy
2017-09-26 17:34 ` Bakul Shah
2017-09-26 17:39 ` Warner Losh
2017-09-26 18:26 ` Bakul Shah
2017-09-26 17:43 ` Larry McVoy
2017-09-26 19:44 ` Grant Taylor
2017-09-26 23:22 ` Wesley Parish
2017-09-25 0:51 ` Charles Anthony
2017-09-25 0:36 ` Dan Cross
2017-09-25 0:44 ` Grant Taylor
2017-09-25 0:56 ` Bakul Shah
2017-09-25 15:45 ` Tony Finch
2017-09-25 16:14 ` Bakul Shah
2017-09-25 7:41 ` Andy Kosela
2017-09-25 7:43 ` Cory Smelosky
2017-09-25 10:14 ` Andy Kosela
2017-09-25 9:58 ` Steve Nickolas
2017-09-25 11:14 ` Derek Fawcus
2017-09-25 11:48 ` Andrew Warkentin
2017-09-24 15:26 ` Christian Barthel
2017-09-24 17:33 ` Clem Cole
2017-09-24 17:33 ` Clem Cole
2017-09-23 23:00 ` Dave Horsfall
2017-09-26 22:00 ` Christian Groessler
2017-09-20 4:42 ` Grant Taylor
2017-09-20 8:31 ` Mutiny
2017-09-20 9:15 ` Steve Nickolas
2017-09-20 16:58 ` Arthur Krewat
2017-09-20 17:05 ` Steve Nickolas
2017-09-20 17:53 ` Henry Bent
2017-09-20 18:12 ` Arthur Krewat
2017-09-20 18:33 ` Brad Spencer
2017-09-20 19:20 ` Henry Bent
2017-09-20 19:37 ` Arthur Krewat
2017-09-20 19:58 ` Jacob Ritorto
2017-09-20 22:29 ` Ian Zimmerman
2017-09-20 22:31 ` Warner Losh
2017-09-20 12:52 ` Chet Ramey
2017-09-20 13:33 ` Nemo
2017-09-20 15:39 ` Clem Cole
2017-09-20 15:42 ` Jon Steinhart
2017-09-20 16:58 ` Ian Zimmerman
2017-09-20 17:09 ` Jon Steinhart
2017-09-20 17:31 ` Arthur Krewat
2017-09-20 22:40 ` Steve Simon
2017-09-20 22:51 ` Erik Berls
2017-09-20 23:37 ` Robert Brockway
2017-09-21 1:47 ` Derrik Walker v2.0
2017-09-21 3:54 ` Gregg Levine
2017-09-21 14:33 ` Nicholas Chappell
2017-09-21 16:38 ` Mutiny
2017-09-21 16:42 ` gilbertmm
2017-09-21 18:30 ` Grant Taylor
2017-09-21 23:34 ` Dave Horsfall
2017-09-25 10:36 ` Thomas Kellar
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