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Date:      Mon, 21 Sep 2020 13:27:01 +0200
From:      Polytropon <freebsd@edvax.de>
To:        "Steve O'Hara-Smith" <steve@sohara.org>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Error message output
Message-ID:  <20200921132701.61bf9883.freebsd@edvax.de>
In-Reply-To: <20200921090937.fc1fbed5bdcd9615d77ea8f4@sohara.org>
References:  <20200920191108.22864e5c.freebsd@edvax.de> <528b2c90-18c4-9e95-a150-67344154c66c@holgerdanske.com> <20200921090937.fc1fbed5bdcd9615d77ea8f4@sohara.org>

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On Mon, 21 Sep 2020 09:09:37 +0100, Steve O'Hara-Smith wrote:
> On Sun, 20 Sep 2020 22:12:24 -0700
> David Christensen <dpchrist@holgerdanske.com> wrote:
> 
> > I have been migrating my programming style towards a data flow paradigm, 
> > which includes "command-line filters".  So, an "ideal" command-line 
> > program or script would:
> > 
> > * Use stdin for the input data.
> > 
> > * Use stdout for the output data.
> > 
> > * Use configuration files, command-line options and arguments, received 
> > signals and direct tty reads for out-of-band/ non-data input.
> 
> 	This is where the standard set of unix devices is lacking, I have
> long thought that there should be a stdctl then stdin/stdout are data flow
> and stdtctl/stderr are control flow.

At least that is something known in "mainframe land": While
the file SYSPRINT is intended for program messages, i. e.,
things the program has to say about what it does, a different
file is used for program output, for example SYSUT2 (but it
doesn't have to be that one). But not everything is that clear:
SYSIN can be used to control the program, but PARM= can also
serve this purpose, while STDIN can instead contain input data
for the program to process.

And don't get me started about DCL... ;-)



-- 
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...



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