GNU bug report logs - #49217
'shuf' returns nothing if the low range number is higher by 1 than the high number

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From: Erik Auerswald <auerswal <at> unix-ag.uni-kl.de>
To: 49217 <at> debbugs.gnu.org
Cc: eggert <at> cs.ucla.edu, the.f8er <at> gmail.com
Subject: bug#49217: 'shuf' returns nothing if the low range number is higher by 1 than the high number
Date: Fri, 25 Jun 2021 08:49:51 +0200

Hi,

On Thu, Jun 24, 2021 at 09:19:36PM -0700, Paul Eggert wrote:
> On 6/24/21 4:46 PM, F8ER F8ER wrote:
> >For example, `shuf -i 101-100 -n 1` returns nothing with the exit code
> >= 0 (unexpected).
> 
> Actually, it's the expected behavior. It's the same behavior as
> 'shuf -n 1 </dev/null'. The '-n 1' option does not mean "output
> exactly 1 line"; it means "output at most 1 line".

I think the reported issue is with producing no error with LO==HI+1,
but producing an error with LO<HI+1:

    $ shuf -i 3-0 ; echo %exit code $?
    shuf: invalid input range: ‘3-0’
    %exit code 1
    $ shuf -i 2-0 ; echo %exit code $?
    shuf: invalid input range: ‘2-0’
    %exit code 1
    $ shuf -i 1-0 ; echo %exit code $?
    %exit code 0

This looks inconsistent and possibly not exactly as intended.

I have taken this example with an older "shuf" from my system, not the
current upstream version:

     shuf --version | head -n1
     shuf (GNU coreutils) 8.28

This is just intended to hopefully clear up a possible misunderstanding,
not to confirm or falsify if the current "shuf" version behaves in the
same way.

HTH, HAND,
Erik
-- 
Object-oriented design is the roman numerals of computing.
                        -- Rob Pike

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