Re: inconsistent behavior of extglobs at start of pattern re dotfiles

Chet Ramey <[email protected]> Wed, 11 Mar 2026 11:13:26 -0400

Newsgroups	gmane.comp.shells.bash.bugs
Organization	ITS, Case Western Reserve University
Message-ID	<[email protected]>

On 3/6/26 12:14 PM, Isaac Z. Schlueter wrote:

> Bash Version: 5.3
> Patch Level: 9
> Release Status: release
> 
> Description:
>    A negative extglob can match the empty string. Also, extglobs that appear
> at the start of a pattern can match a dotfile, if they match a dot
> explicitly.
> 
>    However, a negative extglob (or other extglob matching an empty string)
> that comes ahead of a dot in a pattern will *not* allow that pattern to
> match a dotfile. This seems inconsistent with the "Pathname expansion"
> section, which states only that a '.' at the start (or immediatly following
> a slash) must be "matched explicitly" unless dotglob is set. That is, it
> seems that it *is* being "matched explicitly", but the path is not being
> expanded as expected.

Thanks for the report. The issue is the null pattern in the extglob. The
bash glob code uses a function to determine whether a name should be
skipped instead of run through the matching engine, and that function
didn't allow the null pattern to match a filename beginning with a `.'.

It should allow the name and let the rest of the matcher determine whether
or not to match it. If there are other patterns in the list that begin
with a `.', those are sufficient whether or not there is an empty pattern
in the list, but the empty pattern itself shouldn't disqualify the pattern
list.
-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
		 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    [email protected]    http://tiswww.cwru.edu/~chet/

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