Re: [Buildroot] [PATCH 1/1] fs/common.mk: use find instead of shell glob patterns

[David Laight <David.Laight@ACULAB.COM>]

From: Mat
> Sent: 10 March 2022 11:33
> 
> On Thu, Mar 10, 2022 at 10:45:41AM +0000, David Laight wrote:
> > From: Mathieu Mirmont
> > > Sent: 10 March 2022 10:18
> > >
> > > Different shells can have different behaviours when it comes to
> > > globbing patterns. The dash shell (/bin/sh) on Debian testing switched
> > > to a different fnmatch/glob implementation that results in this new
> > > behaviour:
> > >
> > > Using bash:
> > > $ mkdir /tmp/foo
> > > $ echo /tmp/foo/.[^.]*
> > > /tmp/foo/.[^.]*
> > >
> > > Using dash:
> > > $ mkdir /tmp/foo
> > > $ echo /tmp/foo/.[^.]*
> > > /tmp/foo/..
> >
> > That is just broken.
> > Does the [^x] pattern work at all?
> >
> > Raise a bug on 'Debian testing' hopefully they'll
> > fix it before it actually gets released anywhere.
> 
> The new behaviour of dash is very strange indeed, but also according
> to POSIX the wildcard pattern [^x] is undefined so we should not rely
> on it.

Well [^x] originally meant '^' or 'x' (the same as [x^] but then
shells started treating [^x] the same as [!x].
So I guess POSIX has allowed such shells to be conformant by
making [^x] undefined.

I'm not sure how many shells treat [^x] the same as [!x] but
enough do that people (including me) have forgotten the difference.
ash from a recent buildroot treats [^x] as [!x} but a cygwin
ash I've got doesn't.
A quick search failed to find dash.

ISTR dash is badly broken in other places, try:
$ x=aaab234; echo ${x##${x%%b*}}
b234

It is worth checking whether Debian have changed the behaviour of dash
or whether they've just changed the default root shell to dash.

	David

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