Re: Bash removes unrequested characters in bracket expressions (not a range).

[Bize Ma]

Chet Ramey (<chet.ramey@case.edu>) wrote:

> On 11/24/18 4:32 PM, Bize Ma wrote:

 [...]

> > I have been made aware that there is a
> >       cstart = cend = FOLD (cstart);
> > inside the `sm_loop.c` file that will convert into a range many
> > individual character. If that understanding is correct that is the
> > source of the difference with other shells.
>
> I'm not sure what you mean by "convert into a range." If cstart and cend
> were treated as a range, the start end and end characters would be the
> same. If cstart == cend, a character that collates >= cstart and <= cend
> would have to collate equal to cstart and cend.
>

Yes, exactly, a range where the start and the end are the same.

Try:

$ touch 0 1 ٠ ١  ۰ ۱ ߀ ߁ ० १
$ echo [1]
1  ١

It is converted to the same range as this

$ echo [1-1]
1  ١

That happens because up to glibc 2.27 this has been the collation order of
those characters (search in /usr/share/i18n/locales/iso14651_t1_common) :

<U0030> <0>;<BAS>;<MIN>;IGNORE
<U0660> <0>;<BAS>;<MIN>;IGNORE

Collate to exactly the same values. This breaks the capacity to detect that
a character is absent in a list ordered by the collation order.