Uppercase RE matching problems in FreeBSD 11

[Stefan Ehmann]

On 07.11.2016 22:13, Charles Swiger wrote:
> On Nov 6, 2016, at 1:49 PM, Stefan Bethke <stb at lassitu.de> wrote:
>> Am 06.11.2016 um 22:27 schrieb Baptiste Daroussin
>> <bapt at FreeBSD.org>:
>>> That works for POSIX locale aka C aka ASCII only world
>> 
>> So what do I set my LANG and LC variables to?  I do want UTF-8, but
>> I do also want my scripts to continue to work.  Clearly,
>> en_US.UTF-8 is not what I want.  Is it C.UTF-8?  Or do I set
>> LANG=en_US.UTF-8 and LC_COLLATE=C?
> 
> If you want to use a UTF8 locale, then you must start using character
> classes like '[:upper:]' and '[:lower:]' because those will-- or at
> least "should", modulo bugs-- properly handle the collation issues
> including for languages which do not possess a 1-1 mapping between
> upper and lower case letters.
> 
> Someone with a German email address is presumably familiar with ß /
> Eszett...?  :-)

Character classes work fine for [a-z], but I don't know of a simple way
to match a range like [a-k].

Personally, I prefer the "Rational Range Interpretation" because it
doesn't break backward compatibility and is still standard compliant.