Problem with Bash regex test case sensitivity

Lee ler762@gmail.com
Sat Dec 4 21:08:00 GMT 2010


On 12/4/10, Corinna Vinschen <corinna-cygwin > wrote:
> On Dec  4 10:05, Lee wrote:
>> On 12/3/10, Eric Blake <eblake@ > wrote:
>> > Read the FAQ.  http://www.faqs.org/faqs/unix-faq/shell/bash/, E9.
>>
>> Which says the en_US locale collates the upper and lower case letters like
>> this:
>> 	AaBb...Zz
>>
>> I got that much :)  What I don't get is why someone would _want_ the
>> collating sequence to be AaBb... or why that sequence was picked for
>> en_US instead of using the natural order of A-Za-z.
>
> It's not the "natural" order, it's an arbitrary order which has been
> chosen back in 1963 when the ASCII code has been defined.  It's not used
> as "natural" order outside of computer systems and it's not even the
> natural order on some computer systems (See EBCDIC).

My idea of "natural order" is treating each character as an unsigned
integer.  So even though ASCII has a different collating sequence than
EBCDIC, the characters are still treated as unsigned integers when
sorting them.  Setting LANG to something other than C seems to break
that model..

> If you take a look into a hardcopy encyclopedia written in english,
> you'll be very comfortable that the words are ordered lexicographically
> instead of in ASCII coding, probably.

I never paid all that much attention to how the words were ordered,
but now that I have.. they're backwards!   "god" comes before "God",
"hopper" before "Hopper", etc.

>  Needless to say that ordering
> criteria for non-english languages may contain more characters in the
> sequence, in german for instance
>
>   "AaäBb...Ooö...Ssß...Uuü...Zz"
>
> So, let's reiterate:
>
> - If I need the order for the computer language, I say so:
>
>    LC_COLLATE=C.UTF-8
>
> - Otherwise, if I need the order for the natural language, I say so:
>
>    LC_COLLATE=en_US.UTF-8
>    LC_COLLATE=de_DE.UTF-8

You're quite good at explaining this.. I think I'm actually beginning
to understand it :)
So...  the reason for setting LANG is a shorthand method of setting
all the LC_xxx environment variables?

Thanks,
Lee

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