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Re: Off topic: non zero error codes

From Linux-Fan <Ma_Sys.ma@web.de>
Newsgroups linux.debian.user
Subject Re: Off topic: non zero error codes
Date 2019-05-19 14:00 +0200
Message-ID <xZsDT-1VB-5@gated-at.bofh.it> (permalink)
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Erik Josefsson writes:

> Good morning,
>
> I have wanted to ask for a long time about something I made up from hearsay
> whether it is remotely true. I hope that's OK.
>
> Is there is a shell/language where the returncode for TRUE is zero and that
> that is the opposite of how all other shells/languages are made?

Yes, there is. It is called POSIX shell. Other shells have adpoted the
concept as well, e.g. Bash.

Try:

	$ true
	$ echo $?
	0

	$ false
	$ echo $?
	1

> The argument for creating it was that it then becomes handier to say "no
> errors, one error, two errors..." than to say "success, one error, two
> errors...".

I think it stems from two different traditions:

 * One is to use ``error codes'' to show that something went wrong and 0 if
   everything is OK.

 * The other is to have a function report ``true'' (commonly 1) on success and
   ``false'' (commonly 0) on error.

One can see both traditions used in different styles of C-programs -- some
more advanced programming languages provide the concept of  Exceptions to
avoid these situations, although it is not always consistent even in
comparably new programming languages like Java.

For program execution from the shell, the ``error codes''-idea is applied
and as `true` and `false` are just programs which can be run from the POSIX
shell, the counter-intuitive use of `true` ~ 0 and `false` ~ 1 can be
explained.

HTH
LInux-Fan

[...]

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Salsa vs Github Paul Sutton <zleap@disroot.org> - 2019-05-16 18:00 +0200
  Re: Salsa vs Github Dominik George <natureshadow@debian.org> - 2019-05-16 18:40 +0200
    please do *never* use GitHub for free software, was Re: Salsa vs  Github Mark Allums <mark@allums.email> - 2019-05-17 09:10 +0200
      Re: please do *never* use GitHub for free software, was Re: Salsa vs Github Dominik George <natureshadow@debian.org> - 2019-05-17 09:40 +0200
        Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github <tomas@tuxteam.de> - 2019-05-17 10:40 +0200
          Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github Paul Sutton <zleap@disroot.org> - 2019-05-17 11:00 +0200
        Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github Mark Allums <mark@allums.email> - 2019-05-17 10:40 +0200
          Re: please do *never* use GitHub for free software, was Re: Salsa vs Github Ben Finney <bignose@debian.org> - 2019-05-18 05:50 +0200
            Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github Reco <recoverym4n@enotuniq.net> - 2019-05-18 09:40 +0200
            Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github Mark Allums <mark@allums.email> - 2019-05-18 09:40 +0200
              Re: please do *never* use GitHub for free software, was Re: Salsa vs Github Dominik George <natureshadow@debian.org> - 2019-05-18 10:30 +0200
                Re: please do *never* use GitHub for free software, was Re: Salsa  vs Github Brad Rogers <brad@fineby.me.uk> - 2019-05-18 13:00 +0200
                Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github <tomas@tuxteam.de> - 2019-05-18 15:20 +0200
                Re: please do *never* use GitHub for free software, was Re: Salsa  vs Github Brad Rogers <brad@fineby.me.uk> - 2019-05-18 15:40 +0200
                Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github <tomas@tuxteam.de> - 2019-05-18 15:50 +0200
                Off topic: non zero error codes Erik Josefsson <erik.hjalmar.josefsson@gmail.com> - 2019-05-19 07:30 +0200
                Re: Off topic: non zero error codes Linux-Fan <Ma_Sys.ma@web.de> - 2019-05-19 14:00 +0200
                Re: Off topic: non zero error codes <tomas@tuxteam.de> - 2019-05-19 14:10 +0200
                Re: please do *never* use GitHub for free software, was Re: Salsa vs Github Gene Heskett <gheskett@shentel.net> - 2019-05-18 16:40 +0200
              Re: please do *never* use GitHub for free software, was Re: Salsa vs Github Ben Finney <bignose@debian.org> - 2019-05-19 03:10 +0200
        Re: please do *never* use GitHub for free software, was Re: Salsa vs Github Dominik George <natureshadow@debian.org> - 2019-05-17 18:00 +0200
          Re: please do *never* use GitHub for free software, was Re: Salsa  vs Github arne <sp113438@telfort.nl> - 2019-05-18 01:40 +0200
        Re: please do *never* use GitHub for free software, was Re: Salsa vs Github rhkramer@gmail.com - 2019-05-17 18:00 +0200
          Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github <tomas@tuxteam.de> - 2019-05-17 18:30 +0200
          Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github Alessandro Vesely <vesely@tana.it> - 2019-05-18 10:50 +0200
            Re: please do *never* use GitHub for free software, was Re: Salsa vs Github Dominik George <natureshadow@debian.org> - 2019-05-18 11:00 +0200
              Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github <tomas@tuxteam.de> - 2019-05-18 11:30 +0200
        Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github Aidan Gauland <aidalgol@fastmail.net> - 2019-05-18 00:30 +0200
          Re: please do *never* use GitHub for free software, was Re: Salsa vs Github Dominik George <natureshadow@debian.org> - 2019-05-18 01:10 +0200
            Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github Aidan Gauland <aidalgol@fastmail.net> - 2019-05-18 07:40 +0200
              Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github Richard Hector <richard@walnut.gen.nz> - 2019-05-18 08:10 +0200
                Re: please do *never* use GitHub for free software, was Re: Salsa vs Github Dominik George <natureshadow@debian.org> - 2019-05-18 10:40 +0200
                Re: please do *never* use GitHub for free software, was Re: Salsa  vs Github Curt <curty@free.fr> - 2019-05-18 10:40 +0200
        Re: please do *never* use GitHub for free software, was Re: Salsa vs  Github Rob van der Putten <rob@sput.nl> - 2019-05-18 11:20 +0200
  Re: Salsa vs Github Jonathan Dowland <jmtd@debian.org> - 2019-05-17 11:30 +0200
    Re: Salsa vs Github Paul Sutton <zleap@disroot.org> - 2019-05-17 11:50 +0200
      Re: Salsa vs Github john doe <johndoe65534@mail.com> - 2019-05-17 12:00 +0200
        Re: Salsa vs Github Nate Bargmann <n0nb@n0nb.us> - 2019-05-17 14:20 +0200

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