Re: [bash 4] 'test -v 1' is never true

[Alejandro Colomar]

On 11/27/22 14:10, David wrote:
> On Mon, 28 Nov 2022 at 00:01, Alejandro Colomar <alx.manpages@gmail.com> wrote:
> > On 11/27/22 12:41, Alexey wrote:
> > > On 2022-11-26 21:45, Alejandro Colomar wrote:
>
> > > I could suggest you to use for clarity another construction:
> > > [[ ${1+isset} ]] || echo "not set"
>
> > > Here "isset" is just for readability. You could place any other string literal
> > > there.
>
> > I actually find that very confusing.  What feature is it using?  I couldn't find
> > it with `info bash | less` then `/\+`.
>
> See:
> https://www.gnu.org/software/bash/manual/bash.html#Shell-Parameter-Expansion
> - Under heading: ${parameter:+word}
> - The parameter is 1
> - The word is isset
> - The colon ':' is optional, explained by the sentences beginning with
> "Omitting the colon" ..

Ahh, it was the optional-ness of ':' that bugged me.  I'm also quite 
unaccustomed to [[ expr ]].  :)

Thanks!

Cheers,

Alex


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<http://www.alejandro-colomar.es/>

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