On 11/23/2017 11:57 AM, walter harms wrote:
>
>
> Am 23.11.2017 10:47, schrieb Michael Kerrisk (man-pages):
>> Hi Walter,
>>
>> On 23 November 2017 at 10:23, walter harms <wharms@xxxxxx> wrote:
>>>
>>>
>>> Am 23.11.2017 10:07, schrieb Michael Kerrisk (man-pages):
>>>> On 11/23/2017 09:31 AM, Christoph Hellwig wrote:
>>>>> On Wed, Nov 22, 2017 at 07:15:45PM -0500, Wesley Aptekar-Cassels wrote:
>>>>>> This patch documents the values of error numbers on linux. This is
>>>>>> something that is in the OpenBSD errno man page, which I find quite
>>>>>> useful.
>>>>>
>>>>> Error numbers are different for different architectures.
>>>>
>>>> I was just about to say the same.
>>>>
>>>> Someone else recently proposed the same change, and I should have
>>>> thought then to add the text that I have added just now to errno(3).
>>>> Hopefully this goes someway to addressing your requirements, Wesley.
>>>>
>>>> New text:
>>>>
>>>> On Linux, the error numbers that correspond to each symbolic name
>>>> vary somewhat across architectures. Therefore, numeric values are
>>>> not included in the list of error names below. On any particular
>>>> system, one can obtain a list of all symbolic error names and the
>>>> corresponding error numbers using the errno(1) command:
>>>>
>>> If i read this that would mean the values differ between the linux architectures only.
>>> I do not ting that was intended.
>>
>> Indeed. So, I changed the text to:
>>
>> The error numbers that correspond to each symbolic name vary
>> across UNIX systems, and even across different architectures on
>> Linux. Therefore, numeric values are not included in the list of
>> error names below. Portable applications should use the symbolic
>> error names (rather than explicit error numbers). The perror(3)
>> and strerror(3) functions can be used to convert these names to
>> corresponding textual error messages.
>>
>>> What about that:
>>>
>>>
>>> Portability:
>>> Programmers should use always the symbolic names as that the value of errno may vary
>>> across different systems. Always use strerror (3) (or compareable) to translate
>>> the errno code into a human readable string.
>>>
>>> note: errno (1) is a nice programm and it could be mentioned but a propper programm
>>> simply should not say things like "Error: 13".
>>
>> I'm not sure what you are referring to with the preceding line.
>>
>
> I would move the bulk of the text to a portability section or like because this is
> the section where i would expect that information.
Moving this off into a separate section doesn't really fit with the
overall structure of the page, I think. (All changes are pushed to Git
now, so you can take a look.) So, I'll leave things as they
are for now.
> NTL i was not aware that different linux versions have different code for the same
> error that should be changed.
> Also i would drop "Portable" simply write "applications should use ..." there
> is no reason to write programms that require the numeric value. Corner cases may exists
> but a man page is no law, so i see no problem.
So, I think what this convinces me to do is just drop this sentence:
Portable applications should use the symbolic error names
(rather than explicit error numbers).
I think you're right that it does not add much to the discussion.
Thanks,
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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