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Date: Thu, 14 Aug 2014 17:44:34 -0700
From: Alfred Perlstein <bright@mu.org>
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To: Phil Shafer <phil@juniper.net>, Warner Losh <imp@bsdimp.com>
Subject: Re: XML Output: libxo - provide single API to output TXT, XML, JSON
 and HTML
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Cc: Marcel Moolenaar <marcel@freebsd.org>, John-Mark Gurney <jmg@funkthat.com>,
 "Simon J. Gerraty" <sjg@juniper.net>, arch@freebsd.org,
 Poul-Henning Kamp <phk@phk.freebsd.dk>,
 freebsd-arch <freebsd-arch@freebsd.org>,
 Konstantin Belousov <kostikbel@gmail.com>
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On 8/14/14 9:40 AM, Phil Shafer wrote:
> Warner Losh writes:
>> My question for people advocating this method: Why not require all
>> commands that generate this kind of output to support a standard
>> command line option that causes the command to print nothing and
>> return 0 if it supports reporting, or anything else if it doesn't
>> (return 0 with output, or return non-zero with or without output).
> It's a chicken and egg problem.  I can't call the command with the
> option until I know that command can handle the option without
> generating an error, a core file, or rebooting the box.  Until I
> know what the command will do, I can't invoke it safely.
>
> There's also the issue of find an option that all commands are not
> using, given that I can't change options for existing commands.
>
>
I don't understand the need to query these programs for support of the 
option.

Can you explain in more detail?

-Alfred