GNU bug report logs - #66253
sort manpage should be more explicit

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Package: coreutils;

Reported by: Jorge Stolfi <stolfi <at> ic.unicamp.br>

Date: Thu, 28 Sep 2023 10:17:03 UTC

Severity: normal

Done: Pádraig Brady <P <at> draigBrady.com>

Bug is archived. No further changes may be made.

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Pádraig Brady <P <at> draigBrady.com>
Cc: tracker <at> debbugs.gnu.org
Subject: bug#66253: closed (sort manpage should be more explicit)
Date: Thu, 28 Sep 2023 11:23:02 +0000
[Message part 1 (text/plain, inline)]
Your message dated Thu, 28 Sep 2023 12:22:35 +0100
with message-id <ab3f8de1-b28f-294a-9c3e-8b938401964a <at> draigBrady.com>
and subject line Re: bug#66253: sort manpage should be more explicit
has caused the debbugs.gnu.org bug report #66253,
regarding sort manpage should be more explicit
to be marked as done.

(If you believe you have received this mail in error, please contact
help-debbugs <at> gnu.org.)


-- 
66253: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=66253
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[Message part 2 (message/rfc822, inline)]
From: Jorge Stolfi <stolfi <at> ic.unicamp.br>
To: bug-coreutils <at> gnu.org
Subject: sort manpage should be more explicit
Date: Thu, 28 Sep 2023 07:11:50 -0300
The full documentation of sort explains that numeric sorting (as in  
"sort -n") accepts a leading "-" sign, decimal points, thousands  
separators, etc, but does not accept an explicit "+" sign. Values with  
explicit "+" are treated as numeric 0 and ties are broken by alpha sort.

However, the manpage only says that "-n" "compares according to string  
numerical value" -- and one would expect the numerical value of "+100"  
to be 100, not zero.

It took me an hour to figure out that my "sort -n" was failing because  
of this "feature".  Surely many users have wasted time too, or worse.  
So please either

1) explain precisely IN THE MANPAGE what is a valid number;

2) make numeric sort accept a leading "+", as users would expect;

3) make numeric sort abort with an error message if any field that is  
supposed to be sorted numerically is not a valid number.

I think the best solution for users would be to implement all three of  
these...

Thank you, and all the best

--jorge

-- 
Jorge Stolfi - Professor Titular/Full Professor
Instituto de Computação/Computer Science Dept
Universidade Estadual de Campinas/State University of Campinas
Campinas, SP - Brazil



[Message part 3 (message/rfc822, inline)]
From: Pádraig Brady <P <at> draigBrady.com>
To: Jorge Stolfi <stolfi <at> ic.unicamp.br>, 66253-done <at> debbugs.gnu.org
Subject: Re: bug#66253: sort manpage should be more explicit
Date: Thu, 28 Sep 2023 12:22:35 +0100
On 28/09/2023 11:11, Jorge Stolfi wrote:
> The full documentation of sort explains that numeric sorting (as in
> "sort -n") accepts a leading "-" sign, decimal points, thousands
> separators, etc, but does not accept an explicit "+" sign. Values with
> explicit "+" are treated as numeric 0 and ties are broken by alpha sort.
> 
> However, the manpage only says that "-n" "compares according to string
> numerical value" -- and one would expect the numerical value of "+100"
> to be 100, not zero.
> 
> It took me an hour to figure out that my "sort -n" was failing because
> of this "feature".  Surely many users have wasted time too, or worse.
> So please either
> 
> 1) explain precisely IN THE MANPAGE what is a valid number;
> 
> 2) make numeric sort accept a leading "+", as users would expect;
> 
> 3) make numeric sort abort with an error message if any field that is
> supposed to be sorted numerically is not a valid number.
> 
> I think the best solution for users would be to implement all three of
> these...
> 
> Thank you, and all the best

Note the --debug option really helps with all this:

  $ printf '%s\n' '+4' ' 5' '-1,2.3' | sort -s -n --debug
  sort: note numbers use ‘.’ as a decimal point in this locale
  -1,2.3
  ______
  +4
  ^ no match for key
   5
   _


In saying that, sorting numbers is such a common use case,
it's probably worth adding an extra couple of lines to the man page.
I think I'll apply the following later:

  -n, --numeric-sort          compare according to string numerical value.
                                leading blanks, negative sign, decimal point,
                                and thousands separators are supported.

cheers,
Pádraig


This bug report was last modified 1 year and 270 days ago.

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