Re: Dealing with character ranges in grep

[Paul Eggert]

On 06/08/2011 10:14 PM, Aharon Robbins wrote:

> So, for the upcoming gawk 4.0, I decided (as Karl put it) to cut the
> Gordian knot and make ranges behave like the C locale, the way it's long
> been documented, and as most people expect.  Those who want the POSIX
> behavior can still get it using --posix.

This comment and the ensuing thread seems to be assuming old POSIX.
In new POSIX, that is, in POSIX 1003.1-2008, the standardization committee
removed the old, bogus requirement of using collating element order.
The new rule is that the regular expression [a-z] has an unspecified
behavior outside the C (or POSIX) locale.  So the new gawk behavior
will conform to POSIX, even without the --posix option.

I suggest that gawk's behavior for [a-z] be the same regardless of whether
--posix is specified, and that this behavior be what users expect
(namely, the ASCII character range).  This will be simpler.

Similarly for grep, glibc, etc.

For the POSIX 1003.1-2008 rule, see rule 7 of:

http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_03_05

and for the reasoning behind the rule change, see:

http://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xbd_chap09.html#tag_21_09_03_05