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

From: Paul Eggert <[email-masked]>
Date: Tue, 19 Mar 2024 15:07:01 -0700

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.