Subject: Re: sort behavior [was: bug#9808: bug report]

From: Eric Blake <[email-masked]>
Date: Thu, 20 Oct 2011 07:48:58 -0600

tag 9808 = notabug
thanks

Re-adding the list, so that others may benefit from the solution or 
chime in with suggestions.

On 10/20/2011 07:36 AM, mohamad hadi kianersi wrote:
> yes,but view these
>
> 1.
> [hadi@hadi ~]$  printf '10 a\n1 b\n2 c\n' | sort -k1,1 -r -n
> 10 a
> 2 c
> 1 b
>
> but
> [hadi@hadi ~]$  printf '10 a\n1 b\n2 c\n' | sort -k1,1r -n
> 2 c
> 10 a
> 1 b
> cant sorted with numeric

Did you try 'sort --debug' like I suggested?

$ printf '10 a\n1 b\n2 c\n' | LC_ALL=C sort -k1,1r -n --debug
sort: using simple byte comparison
sort: option `-n' is ignored
2 c
_
___
10 a
__
____
1 b
_
___

Notice - sort is _correctly_ ignoring -n, and --debug even tells you so, 
per the rules given by POSIX:
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sort.html

"The following options shall override the default ordering rules. When 
ordering options appear independent of any key field specifications, the 
requested field ordering rules shall be applied globally to all sort 
keys. When attached to a specific key (see -k), the specified ordering 
options shall override all global ordering options for that key." [d, f, 
i, n, r]

That is, the moment you use -k with r attached, then the global -n no 
longer applies to that -k; to get both r and n behavior on a single key, 
you have to attach both options to that -k:

$ printf '10 a\n1 b\n2 c\n' | LC_ALL=C sort -k1,1rn --debug
sort: using simple byte comparison
10 a
__
____
2 c
_
___
1 b
_
___

As such, I'm closing this bug report, now that we know the problem was a 
usage error and not a bug in sort.

-- 
Eric Blake   [email-masked]    +1-801-349-2682
Libvirt virtualization library http://libvirt.org