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From: Janis Papanagnou <janis_papanagnou+ng@hotmail.com>
Newsgroups: comp.unix.shell
Subject: Re: coproc or whatever in bash and ksh (Was: Different variable
 assignments)
Date: Sat, 19 Oct 2024 16:11:44 +0200
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On 19.10.2024 15:54, Janis Papanagnou wrote:
>>>> Lawrence D'Oliveiro  <ldo@nz.invalid> wrote:
>>>>>
>>>>>    coproc { uname -sr; }
>>>>>    read -u ${COPROC[0]} var3
>>>>>    wait $COPROC_PID
>>>>>    echo $var3
>>>>
> 
> The syntax for the [unnecessary] co-process application depicted
> above would in Ksh be
> 
>   uname -sr |&
>   read -p var
>   echo "$var"

Concerning the syntax (differences, and generally) I want to add
that it's worthwhile to compare the Ksh syntax with the approach
that we would typically take [in Ksh] to solve the task

  uname -sr | read var
  echo "$var"

We see that the co-process syntax is a straightforward variant of
the ordinary piping. (As opposed to bash that introduces a lot of
[bulky] stuff that's not even resembling in any way the read-pipe.)


For the interested folks let me hijack my post to add that it's
possible to redirect the co-processes to other file descriptors
(using <&p and >&p with appropriate file descriptor numbers) so
that multiple co-processes can be simultaneously used.

Janis