Re: whats wrong with (( a = 8 , a > 4 && a -= 2 || a-- )) , bash: ((: a = 8 , a > 4 && a -= 2 || a-- : attempted assignment to non-variable (error token is "-= 2 || a-- ")

[alex xmb ratchev]

On Thu, Mar 23, 2023, 17:07 Reuti <reuti@staff.uni-marburg.de> wrote:

>
> > Am 23.03.2023 um 16:53 schrieb Bipul kumar <bipul.opensource@gmail.com>:
> >
> > Hi Alex,
> >
> > It's failing because, what you are doing is compound assignment
> >  a -= 2
> > which needs to be inside parentheses.
> > It works for me.
> > (( a = 8 , a > 4 && (a -= 2) || a-- ))
> > $ echo $a
> > 6
>
> It only evaluates (a -= 2) in the logical AND plus OR expression. This
> might work under certain circumstances, i.e. as long as ( a -= 2 ) is not
> zero:
>
> $ (( a = 8 , a > 4 && (a -= 8) || a-- ))
> $ echo $a
> -1
>

thank you sir

-- Reuti
>
>
> > source https://www.gnu.org/software/bash/manual/bash.html    search
> > "compound assignment"
> >
> >    Respectfully,
> >    Bipul
> >    PUBLIC KEY <http://ix.io/1nWf>
> >    97F0 2E08 7DE7 D538 BDFA  B708 86D8 BE27 8196 D466
> >                    ** Please excuse brevity and typos. **
> >
> >
> > On Thu, Mar 23, 2023 at 4:03 PM alex xmb ratchev <fxmbsw7@gmail.com>
> wrote:
> >
> >> i remember doing && (( code
> >> maybe i didnt '=' in action there
> >>
> >> (( a = 8 , a > 4 && a -= 2 || a-- ))
> >>
> >> bash: ((: a = 8 , a > 4 && a -= 2 || a-- : attempted assignment to
> >> non-variable (error token is "-= 2 || a-- ")
> >>
> >>
> >> (( a = 8 , a > 4 && a-- && a-- || a-- ))
> >>
> >> works
> >> a=6
> >>
> >> ..
> >> i suppose this is a (( lex bug where u didnt include || && in op for =
> >>
> >> is it ? :))
> >>
> >> greets
> >>
>
>