Re: Zero-length indexed arrays

[L A Walsh]

On 2021/12/21 20:07, Greg Wooledge wrote:
> On Tue, Dec 21, 2021 at 10:48:07PM -0500, Dale R. Worley wrote:
>   
> > Lawrence Vel�zquez <vq@larryv.me> writes:
> >     
> > > Did you mean to say that ${#FOO[*]} causes an error?  Because
> > > ${FOO[*]} does not, a la $*:
> > >       
> > The case that matters for me is the Bash that ships with "Oracle Linux".
> > Which turns out to be version 4.2.46(2) from 2011, which is a lot older
> > than I would expect.  But it *does* cause an error in that verison:
> >
> >     $ ( set -u ; FOO=() ; echo "${FOO[@]}" )
> >     bash: FOO[@]: unbound variable
> >     

> > I would recommend not using set -u.  It's not as bad as set -e, but it's
> > still pretty bad.  It breaks what would otherwise be valid scripts, and
> > the breakage is not always easy to predict, as you've now seen.
----
   Not using '-u' in bash is akin to not using 'strict' in perl.  you 
can put int misspelled variables
and not detect them -- and then wonder why your scripts don't work.

If you adhere to always requiring a definition of a variable, then using 
'-u' is never a problem.
But not using '-u', in a script where all variables are defined will 
show unintended errors.

They key is to always require definitions, which is why I always rely on
alias my='declare '
to shorten my declares.