Linus Torvalds wrote:
> On Sun, Mar 14, 2021 at 7:32 PM Rong Chen <rong.a.chen@intel.com> wrote:
> >
> > It can be reproduced with '-a' option in dash:
> 
> Oh, ok. That kind of explains it.
> 
> 'dash' is trash. Please somebody make a bug report.
> 
> >      $ a="!"
> >      $ [ "$a" = ".size" ]
> >      $ [ "$a" = ".size" -a "$b" = ".LPBX0," ]
> >      sh: 2: [: =: unexpected operator
> 
> This is 100% a dash bug. There is no question what-so-ever about it.
> This is not some kind of "POSIX is ambiguous", or "the handling of
> '-a' is complicated".
> 
> It's simply just that dash is buggy.
> 
> >  While dash supports most uses of the -a and -o options, they have
> > very confusing semantics even in bash and are best avoided.
> 
> No, they have perfectly sane semantics in bash, and in POSIX.
> 
> See
> 
>      https://pubs.opengroup.org/onlinepubs/9699919799/utilities/test.html
> 
> and there is absolutely zero question that bash does this correctly,
> and dash does not.
> 
> But yes, it seems to be easy to work around, but still - could some
> Ubuntu person please open a bug report on dash?

fwiw, https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=850202