bug#41563: Possible bug with 'sort -Vr' version sorting

[Kamil Dudka]

On Wednesday, May 27, 2020 2:07:32 PM CEST Danie de Jager via GNU coreutils 
Bug Reports wrote:
> Hi,
> 
> I use sort -Vr to sort version numbers. I noticed this discrepancy on
> the latest kernel version from Centos 7.8.
> 
> command to get output:
> # ls -t /boot/vmlinuz-* | sed "s/\/boot\/vmlinuz-//g" | grep -v rescue
> 
> | sort -Vr
> 
> 3.10.0-1127.el7.x86_64
> 3.10.0-1127.8.2.el7.x86_64
> 3.10.0-1062.18.1.el7.x86_64

It is the underscore in the .x86_64 suffix what breaks the version compare 
algorithm.  If you replace the underscore by an alphabetic character, it
sorts as you expect:

# ls -t /boot/vmlinuz-* | sed "s/\/boot\/vmlinuz-//g" | grep -v rescue | \
    sed 's/x86_64/x86X64/' | sort -Vr | sed 's/x86X64/x86_64/'

3.10.0-1127.8.2.el7.x86_64
3.10.0-1127.el7.x86_64
3.10.0-1062.18.1.el7.x86_64

Kamil

> I'd expect the middle value to be the highest version number. Is this
> by design or a bug? If it is a bug please let me know if I must log it
> somewhere.
> 
> Version details:
> # sort --version
> sort (GNU coreutils) 8.22
> Copyright (C) 2013 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later
> <http://gnu.org/licenses/gpl.html>. This is free software: you are free to
> change and redistribute it. There is NO WARRANTY, to the extent permitted
> by law.
> 
> Written by Mike Haertel and Paul Eggert.
> 
> Regards,
> Danie de Jager