Why does the pattern matching expression [A-Z]* match files beginning with every letter except `z'?

Why does the pattern matching expression [A-Z]* match files beginning with every letter except `z'? 


Bash-2.05 and later versions have reverted to the bash-2.03 behavior of

honoring the current locale setting when processing ranges within pattern

matching bracket expressions ([A-Z]).  This is what POSIX.2 and SUSv3/XPG6

specify. 



The behavior of the matcher in bash-2.05 and later versions depends on the

current LC_COLLATE setting.  Setting this variable to `C' or `POSIX' will

result in the traditional behavior ([A-Z] matches all uppercase ASCII

characters).  Many other locales, including the en_US locale (the default

on many US versions of Linux) collate the upper and lower case letters like

this:



	AaBb...Zz



which means that [A-Z] matches every letter except `z'.  Others collate like



	aAbBcC...zZ



which means that [A-Z] matches every letter except `a'.



The portable way to specify upper case letters is [:upper:] instead of

A-Z; lower case may be specified as [:lower:] instead of a-z.



Look at the manual pages for setlocale(3), strcoll(3), and, if it is

present, locale(1).  If you have locale(1), you can use it to find

your current locale information even if you do not have any of the

LC_ variables set.



My advice is to put



	export LC_COLLATE=C



into /etc/profile and inspect any shell scripts run from cron for

constructs like [A-Z].  This will prevent things like



	rm [A-Z]*



from removing every file in the current directory except those beginning

with `z' and still allow individual users to change the collation order.

Users may put the above command into their own profiles as well, of course.

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