bug#9128: [PATCH] Fix handling of non-numeric keys with '-n'

[Eric Blake]

tag 9128 notabug
thanks

On 07/20/2011 03:01 AM, Zdenek Pavlas wrote:
> There's a possible BUG when using '-n' that any non-numeric key is handled
> as equal to '0'. This results in unexpected behavior eg. when using '-nu'.

Thanks for the report.  However, this behavior is required by POSIX:

http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sort.html

-n
    Restrict the sort key to an initial numeric string, consisting of 
optional <blank> characters, optional minus-sign, and zero or more 
digits with an optional radix character and thousands separators (as 
defined in the current locale), which shall be sorted by arithmetic 
value. An empty digit string shall be treated as zero. Leading zeros and 
signs on zeros shall not affect ordering.

On the line "NUMBERS", the initial numeric string is empty, hence the 
line is sorted with the value of 0.

> +++ b/src/sort.c
> @@ -1907,6 +1907,17 @@ numcompare (char const *a, char const *b)
>     while (blanks[to_uchar (*b)])
>       b++;
>
> +  /* Put non-numeric keys before all numbers.
> +     If both non-numeric, don't return 0 unless equal. */
> +  if (!ISDIGIT(*a)&&  *a != '-') {

Sorry, we can't take this patch, as it would violate POSIX and probably 
break existing scripts that expect sort to treat non-numeric lines as 
sorting identically with 0.

--
Eric Blake   address@hidden    +1-801-349-2682
Libvirt virtualization library http://libvirt.org