Subject: bug#69901: closed (Re: bug#69901: (echo a; echo b) | sort -nu looses some data)

From: [email-masked] (GNU bug Tracking System)
Date: Tue, 19 Mar 2024 22:08:02 +0000

Your bug report

#69901: (echo a; echo b) | sort -nu  looses some data

which was filed against the coreutils package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to [email-masked].

-- 
69901: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=69901
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Subject: Re: bug#69901: (echo a; echo b) | sort -nu looses some data
From: Paul Eggert <[email-masked]>
To: Rafal Maszkowski <[email-masked]>
Cc: [email-masked]
Date: Tue, 19 Mar 2024 15:07:01 -0700
List-Id: <debbugs-submit.debbugs.gnu.org>

On 3/19/24 08:33, Rafal Maszkowski wrote:
> he --debug option advised in
> README does not say anything helpful:
> 
> (echo a; echo b) | sort --debug -nu
> sort: text ordering performed using simple byte comparison
> a
> ^ no match for key

That diagnostic message is helpful. It's telling you that there's no 
number, so everything sorts as being the same, which means 'sort -nu' 
(correctly) outputs just one line.

'sort' has behaved this way for quite some time, and POSIX requires this 
behavior.

Subject: (echo a; echo b) | sort -nu looses some data
From: Rafal Maszkowski <[email-masked]>
To: [email-masked]
Date: Tue, 19 Mar 2024 16:33:09 +0100
List-Id: <debbugs-submit.debbugs.gnu.org>

Sort with -n and -u options works correctly for numbers:

(echo 10; echo 11) | sort -nu
10
11

but looses data when used with non-numbers:

(echo a; echo b) | sort -nu
a

(echo 1.0; echo 1.1) | sort -nu
1.0

I have tested this on versions 8.32 and 9.2 default for Debian 11 and
12, and additionally compiled version 9.4. The --debug option advised in
README does not say anything helpful:

(echo a; echo b) | sort --debug -nu
sort: text ordering performed using simple byte comparison
a
^ no match for key

R.
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