Re: Different variable assignments

From	Frank Winkler <usenet@f.winkler-ka.de>
Newsgroups	comp.unix.shell
Subject	Re: Different variable assignments
Date	2024-10-12 09:42 +0200
Message-ID	<lmuniuF632tU1@mid.individual.net> (permalink)
References	<lmt83dFsvbvU3@mid.individual.net> <lmt90sFr1idU1@mid.individual.net> <lmta1jFsvc0U1@mid.individual.net> <vecl6n$d0r$1@dont-email.me>

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On 12.10.2024 03:59, Janis Papanagnou wrote:

  >It depends on your shell. If you choose Kornshell you won't have that
  >issue and can write it as you've done with the output as you'd expect.
  >
  >$ uname -a | read var
  >$ echo "$var"
  >Linux [...snip...]
  >
  >The reason is that the last command in a pipeline will (in Kornshell)
  >be executed in the "current" shell context.

Interesting hint! I wasn't aware that there are such differences between 
the shells. And indeed, some simple tests seem to work in an interactive 
ksh.

Let's see the whole story. For historical reasons, I'm actually using 
ksh for almost all scripts instead of bash for interactive use - not 
knowing about the fact above.

There, I run command A which is producing output and which is calling 
sub-command B, also producing output. This works fine.
What I want to achieve is to grab some parts of the output and store it 
in a variable but without changing the output on the screen.

So I tried something like

tty=`tty`
A | tee $tty | ... | read var

"tee `tty`" inside the command fails, so I do it outside. The output of 
A is still there but B's is gone (because B doesn't know anything about 
the "tee"?) and the whole thing doesn't seem to be still working. $var 
is empty, though this is a ksh script and the stuff behind "tee" is also 
working.
To my understanding, the default B can be changed with an option but 
when I set it to "B | tee $tty", there's still no output.

AFAIR, "var=`...`" works better but as the primary job is the command 
itself and the variable is just a spin-off product, I'd prefer to do the 
assignment at the end. I believe it looks better then ;) ...

Probably it would also be feasible with some temp files but I try to 
avoid them wherever possible.

Happy week-end!

	fw

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Different variable assignments Frank Winkler <usenet@f.winkler-ka.de> - 2024-10-11 20:11 +0200
  Re: Different variable assignments John-Paul Stewart <jpstewart@personalprojects.net> - 2024-10-11 14:27 -0400
    Re: Different variable assignments Frank Winkler <usenet@f.winkler-ka.de> - 2024-10-11 20:45 +0200
      Re: Different variable assignments Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-12 03:59 +0200
        Re: Different variable assignments Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-12 02:26 +0000
          Re: Different variable assignments gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-19 10:45 +0000
            Re: Different variable assignments Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-19 14:25 +0200
              coprocs in bash & ksh (Was: Different variable assignments) gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-19 13:39 +0000
                Re: coprocs in bash & ksh (Was: Different variable assignments) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-19 15:57 +0200
        Re: Different variable assignments Frank Winkler <usenet@f.winkler-ka.de> - 2024-10-12 09:42 +0200
          Re: Different variable assignments Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-12 07:51 +0000
          Re: Different variable assignments Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-12 13:08 +0200
            Re: Different variable assignments Lem Novantotto <Lem@none.invalid> - 2024-10-12 12:01 +0000
              Re: Different variable assignments Frank Winkler <usenet@f.winkler-ka.de> - 2024-10-12 17:57 +0200
                Re: Different variable assignments Lem Novantotto <Lem@none.invalid> - 2024-10-12 17:09 +0000
                lastpipe (Was: Different variable assignments) gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-19 11:47 +0000
                Re: lastpipe (Was: Different variable assignments) Lem Novantotto <Lem@none.invalid> - 2024-10-19 12:53 +0000
                Re: Different variable assignments Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-12 21:32 +0000
                Re: Different variable assignments Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-12 23:47 +0200
                Re: Different variable assignments Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-12 21:50 +0000
                Re: Different variable assignments Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-12 23:56 +0200
                Re: Different variable assignments Lem Novantotto <Lem@none.invalid> - 2024-10-12 23:07 +0000
                Re: Different variable assignments Lem Novantotto <Lem@none.invalid> - 2024-10-12 23:10 +0000
                Re: Different variable assignments Lem Novantotto <Lem@none.invalid> - 2024-10-12 23:39 +0000
                Re: Different variable assignments Frank Winkler <usenet@f.winkler-ka.de> - 2024-10-15 13:46 +0200
                Re: Different variable assignments Frank Winkler <usenet@f.winkler-ka.de> - 2024-10-24 11:30 +0200
                Re: Different variable assignments gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-24 11:21 +0000
                Re: Different variable assignments Frank Winkler <usenet@f.winkler-ka.de> - 2024-10-24 23:43 +0200
                Re: Different variable assignments Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-25 06:57 +0200
                Re: Different variable assignments Lem Novantotto <Lem@none.invalid> - 2024-10-24 22:45 +0000
                tee with no args is a no-op (Was: Different variable assignments) gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-25 07:10 +0000
                Re: tee with no args is a no-op (Was: Different variable assignments) Lem Novantotto <Lem@none.invalid> - 2024-10-25 08:57 +0000
            Re: Different variable assignments Frank Winkler <usenet@f.winkler-ka.de> - 2024-10-12 17:49 +0200
        lastpipe (Was: Different variable assignments) gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-19 11:50 +0000
  Re: Different variable assignments Helmut Waitzmann <nn.throttle@xoxy.net> - 2024-10-11 22:20 +0200
    Re: Different variable assignments Frank Winkler <usenet@f.winkler-ka.de> - 2024-10-11 22:50 +0200
      Re: Different variable assignments Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-11 21:03 +0000
        Re: Different variable assignments gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-19 11:45 +0000
          Re: Different variable assignments Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-19 14:52 +0200
            coproc or whatever in bash and ksh (Was: Different variable assignments) gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-19 13:35 +0000
              Re: coproc or whatever in bash and ksh (Was: Different variable assignments) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-19 15:54 +0200
                Re: coproc or whatever in bash and ksh (Was: Different variable assignments) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-19 16:11 +0200
                Re: coproc or whatever in bash and ksh (Was: Different variable assignments) gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-19 14:52 +0000
            Re: Different variable assignments Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-19 21:42 +0000
              Re: Different variable assignments gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-19 22:56 +0000
                Re: Different variable assignments Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-20 07:09 +0200
                coprocs - again (Was: Different variable assignments) gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-20 09:12 +0000
                Re: coprocs - again (Was: Different variable assignments) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-25 06:26 +0200
                Re: coprocs - again (Was: Different variable assignments) Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-10-25 04:35 +0000
                Re: coprocs - again (Was: Different variable assignments) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-25 07:03 +0200
                Subjective "valuations" are all we have (Was: coprocs - again (Was: Different variable assignments)) gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-25 08:10 +0000
                Re: Subjective "valuations" are all we have (Was: coprocs - again (Was: Different variable assignments)) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-25 11:32 +0200
                Re: Subjective "valuations" are all we have (Was: coprocs - again (Was: Different variable assignments)) Lem Novantotto <Lem@none.invalid> - 2024-10-25 11:15 +0000
                Re: Subjective "valuations" are all we have (Was: coprocs - again (Was: Different variable assignments)) gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-25 12:54 +0000
                Re: Subjective "valuations" are all we have (Was: coprocs - again (Was: Different variable assignments)) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-10-26 16:20 +0200
                Re: coprocs - again (Was: Different variable assignments) gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-25 07:06 +0000
                How to do multiple concurrent coprocs in ksh (Was: coprocs - again (Was: Different variable assignments)) gazelle@shell.xmission.com (Kenny McCormack) - 2024-10-25 07:05 +0000
      Re: Different variable assignments Christian Weisgerber <naddy@mips.inka.de> - 2024-10-11 23:25 +0000
    Re: Different variable assignments gazelle@shell.xmission.com (Kenny McCormack) - 2024-11-15 10:58 +0000
      Re: Different variable assignments Lem Novantotto <Lem@none.invalid> - 2024-11-16 00:07 +0000

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