Then, I suggest adding after -c :

-c, --check, --check=diagnose-first check for sorted input; do not sort

>> Note that, when selecting fields with -k while using the -c switch, user should probably also disable the last-resort comparison with -s to obtain the expected result.

after -k :

-k, --key=POS1[,POS2] start a key at POS1 (origin 1), end it at POS2 (default end of line)

>> By default, if two lines are considered equivalent regarding the key specification, sort will try to resolve the equivalence by comparing the whole lines. This is called the "last-resort comparison" (and may be disabled with -s)

and after -s :

-s, --stable stabilize sort by disabling last-resort comparison

>> (See -k)

De : Eric Blake <eblake@redhat.com>
À : Camion SPAM <camion_spam-gnubugs@yahoo.fr>
Cc : "14226-done@debbugs.gnu.org" <14226-done@debbugs.gnu.org>
Envoyé le : Samedi 20 avril 2013 17h54
Objet : Re: bug#14226: Sort -c takes in account fields that were outside sorting scope

On 04/19/2013 06:56 PM, Camion SPAM wrote:
> Well, I'm satisfied with your suggestion of adding -s.
> I would just add that this might be something that should be added to the man page.

The man page is generated from 'sort --help', and there, we are trying
to favor brevity. But it might indeed be worth adding to the 'info
sort' page. I read that page, and notice that while '-c' and '-C' are
mentioned first, details about '-k' and '-s' are several screenfuls
away, so it is not obvious that those two options can affect the
behavior of -c. You could help by reading that page, and finding the
spot(s) where adding a sentence would have helped you; if you could
propose the location and wording to add, then we can work with that to
turn it into a formal patch.

--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org