Re: configure scripts rely on "diff"; could use "cmp" instead if available

[Eric Blake]

On 05/25/2011 09:26 AM, Konstantin Andreev wrote:
> On 25.05.11 18:47, Eric Blake wrote:
>> On 05/25/2011 06:40 AM, Konstantin Andreev wrote:
>>>
>>> Why do you refer to GCS? I thought that 'autoconf' is intended for
>>> most Unix'es, not only GNU.
>>
>> Autoconf stated goal is to generate configure scripts that run on all
>> platforms that comply with the GCS set of minimum prerequisites - it
>> so happens that this covers most Unix'es (including proprietary systems).
> 
> Thank you for explanation.
> 
> Just for curiosity, - wouldn't POSIX.2 be a better base for autoconf
> portability ?

No.  My understanding is that the set of programs required by GCS is a
strict subset of POSIX.2; so by targetting the stricter GCS subset, we
cover more platforms than we would by using POSIX.2 as our minimum.
[Disclaimer - I'm more familiar with POSIX 2008, which derives from the
original POSIX.1, and I'm not sure how that differs from POSIX.2]

Besides, very few systems are actually POSIX compliant (many come close,
but that's part of the reason autoconf exists, to work around the places
where there are differences).  To date, I know of no GNU/Linux system
that has ever achieved POSIX certification, although efforts are
certainly being made to close the gaps, and you can probably make the
counterargument that GNU/Linux systems often tend to comply better than
some proprietary systems that have actually passed POSIX compliance
certification (due to holes in the certification testsuites).

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

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