On 04/22/09 11:16, Don Cragun wrote:
>> Date: Tue, 21 Apr 2009 07:48:21 -0700
>> From: "Garrett D'Amore" <gdamore at sun.com>
>> Message-ID: <49EDDCB5.8080700 at sun.com>
>>
>> I. Szczesniak wrote:
> ... ... ...
>>> Could you elaborate the difference between Committed and Committed
>>> Obsolete?
>>>
>>
>> Committed Obsolete means we can't remove it, but you're still
>> discouraged from using it in new code. That's the case with -b -- it
>> is used to indicate a count in blocks (512 bytes), but the option was
>> removed from the POSIX standard over confusion about what was meant
>> by a "block" (is it a block of bytes, or a block of characters?)
>>
> ... ... ...
>>
>> -- Garrett
>
> Garrett,
> I think you misread the tail rationale in the POSIX standard.
> SVID3 had a -b option that counted 512-byte blocks; BSD had a -b option
> that counted 1024-byte blocks. The -b option wasn't removed from POSIX;
> it was never added in the first place due to this difference in
> behavior.
>
> The SVID3 and XPG3 -c options counted in bytes, but the documentation
> said it counted characters (I don't remember what the BSD tail man page
> said). The POSIX committee briefly considered changing the -c option to
> be -b when the description of -c changed from "characters" to "bytes",
> but left it as -c because historical implementations had the -b option
> counting blocks even though it wasn't going to be specified by the
> standard.
>
> The standard does not currently specify a way to count (multi-byte)
> characters even though this means tail output may start or end in the
> middle of a multi-byte character when using the -c option.
Ah, thanks for the clarification. The point is, its ambiguous (512 or
1024), and not part of the standard. So it shouldn't be used in new code.
-- Garrett
>
> - Don
