Re: !(.pattern) can match . and .. if dotglob is enabled

[Chet Ramey]

On 5/26/21 7:36 PM, Nora Platiel wrote:
> Hello,
>
> > This is behavior that changed more than ten years ago.
>
> I thought it changed in this commit:
> https://git.savannah.gnu.org/cgit/bash.git/commit/?id=ac50fbac377e32b98d2de396f016ea81e8ee9961
> 2014-02-26 -> 7.2 years ago

That's the commit to the master branch when bash-4.3 was released. The
actual change, captured in the `devel' branch that tracks bash development,
happened sometime in 2011.

> But yes, I know it's old stuff and I was not implying a regression, just 
> mentioning it FYI.
>
> > There was a relevant discussion back in January:
> > https://lists.gnu.org/archive/html/bug-bash/2021-01/msg00240.html
>
> Thanks, I did a search but I missed it.
> It *is* relevant, because I think that @(?|.?) matching '.' is consistent with 
> !(.foo) matching '.' and '..'

OK, so we're saying the same thing at this point.

> The problem is, there is nothing in the docs that hints at such behavior.
> I.e. that the pattern beginning with a literal dot may not match at all, but it 
> still signal that '.' and '..' should be accepted in the final match.

How would you improve the wording? What do you think is most important to
cover?


> So why it does here?
> $ shopt -s dotglob; echo @(.foo|*)
> . .. .a b
> $ shopt -u dotglob; echo @(.foo|*)
> b

It's not intuitive. The dotglob causes all files starting with `.' to be
in the list, the .foo pattern keeps `.' and `..' from being discarded,
and the `*' matches it (since dotglob disables the requirement that an
initial `.' be matched explicitly).

Can you write a set of rules that encapsulates what you would like to see?
Or can the group?


--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/