GNU bug report logs - #22084
Potential Bug in sort -r

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From: Assaf Gordon <assafgordon <at> gmail.com>
To: Adrià Rovira <adria.rovira <at> upc.edu>, 22084 <at> debbugs.gnu.org
Cc: Deimos Ibanez Segura <deimos.ibanez <at> upc.edu>
Subject: bug#22084: Potential Bug in sort -r
Date: Thu, 3 Dec 2015 12:18:04 -0500

tag 22084 notabug
close 22084
stop

Hello Adrià and Deimos,


On 12/03/2015 07:30 AM, Adrià Rovira wrote:
> I noticed the reverse option is not correctly applied if it has to sort by more than one column.

This is not a bug, but simply a usage issue.
The "sort --help" page states:
" ... OPTS is one or more single-letter ordering options [bdfgiMhnRrV],
which override global ordering options for that key. "

That is,
1. If you use global sorting option (-n), and a key option WITHOUT
   ordering option (e.g. '-k1,1') - the global sorting option is in effect.

2. If you use *any* sorting option in the key specification
 (e.g. '-k1,1r'), it overrides the global sorting option,
 thus the order in effect is just 'reverse' (implying: alphabetical order).

These examples should demonstrate it:

    # Input data
    $ printf "1\n07\n2\n"
    1
    07
    2
    
    # Alphabetical (ascii) sort,
    # character "0" comes before "1"
    $ printf "1\n07\n2\n" | sort
    07
    1
    2
    
    # Numerical sort, value 7 comes after 2
    $ printf "1\n07\n2\n" | sort -n
    1
    2
    07
    
    # Global option (-n), key without ordering option:
    # numeric sort in effect
    $ printf "1\n07\n2\n" | sort -n -k1,1
    1
    2
    07
    
    # Global option (-n), key with any ordering option
    # (in this case 'b' = ignore leading blanks)
    # global numeric ordering is ignore
    $ printf "1\n07\n2\n" | sort -n -k1b,1
    07
    1
    2
    
    # Adding the numeric ordering to the key -
    # takes effect
    $ printf "1\n07\n2\n" | sort -n -k1bn,1
    1
    2
    07


regards,
 - Assaf

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