Re: locale specific ordering in EN_US -- why is a<A<b<B<y<Y<z<Z?

[Greg Wooledge]

On Sun, May 20, 2012 at 11:36:35AM -0700, Linda Walsh wrote:
> Anyway... so WHY does bash collate this way?

It doesn't.  The operating system does.  Bash just calls upon the C
library's strcoll(3) routine.

The results vary across operating systems, and even potentially across
locale definitions within a given OS implementation.

> Under what rules is bash 
> operating?  I.e. justification?

http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap07.html

In particular, LC_COLLATE starts at
http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap07.html#tag_07_03_02

> If other programs claim to have locale specific sorting & character 
> collation,  should they be sorting the same way? 

Yes.  ls(1) for example sorts filenames according to the collation
order defined in the current locale (LC_ALL or LC_COLLATE or LANG).
You should get the same sorting from both ls and *.

For instance, on HP-UX 10.20, in the en_US.iso88591 locale:

imadev:~$ mkdir /tmp/greg && cd "$_"
imadev:/tmp/greg$ touch a A á Á à À â Â ä Ä b B
imadev:/tmp/greg$ ls
A  a  Á  á  À  à  Â  â  Ä  ä  B  b
imadev:/tmp/greg$ echo *
A a Á á À à Â â Ä ä B b
imadev:/tmp/greg$ LC_COLLATE=C ls
A  B  a  b  À  Á  Â  Ä  à  á  â  ä
imadev:/tmp/greg$ LC_COLLATE=C; echo *; unset LC_COLLATE
A B a b À Á Â Ä à á â ä

Meanwhile, on Debian 6.0, in the en_US.iso88591 locale:

arc3:~$ mkdir /tmp/greg && cd "$_"
arc3:/tmp/greg$ touch a A á Á à À â Â ä Ä b B
arc3:/tmp/greg$ echo *
a A á Á à À â Â ä Ä b B

As you can see, the two en_US.iso88591 implementations are not the same.

See http://mywiki.wooledge.org/locale or myriad other resources (including
the POSIX page linked earlier) for further explanations.