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?

               Linus