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* Precedence of operations in [[
@ 2018-12-03 15:14 ` Peng Yu
  2018-12-03 15:57   ` Peter Stephenson
  0 siblings, 1 reply; 2+ messages in thread
From: Peng Yu @ 2018-12-03 15:14 UTC (permalink / raw)
  To: zsh-users

Hi,

It seems that there is precedence of the operations in [[. For
example, && is of a higher precedence than ||. I don't find where it
is documented in the man page. Could anybody show me? Thanks.

I see ARITHMETIC EVALUATION discusses precedence. But I don't think it
is for [[.

$ ./main.sh
for x1 in '' x
do
    for x2 in '' x
    do
        for x3 in '' x
        do
            echo "==> $x1, $x2, $x3 <=="
            [[ $x1 || $x2 && $x3 ]]
             echo $?
            [[ $x1 || ($x2 && $x3) ]]
             echo $?
            [[ ($x1 || $x2) && $x3 ]]
         echo $?
        done
    done
done
==> , ,  <==
1
1
1
==> , , x <==
1
1
1
==> , x,  <==
1
1
1
==> , x, x <==
0
0
0
==> x, ,  <==
0
0
1
==> x, , x <==
0
0
0
==> x, x,  <==
0
0
1
==> x, x, x <==
0
0
0

-- 
Regards,
Peng

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: Precedence of operations in [[
  2018-12-03 15:14 ` Precedence of operations in [[ Peng Yu
@ 2018-12-03 15:57   ` Peter Stephenson
  0 siblings, 0 replies; 2+ messages in thread
From: Peter Stephenson @ 2018-12-03 15:57 UTC (permalink / raw)
  To: zsh-users

On Mon, 2018-12-03 at 09:14 -0600, Peng Yu wrote:
> It seems that there is precedence of the operations in [[. For
> example, && is of a higher precedence than ||. I don't find where it
> is documented in the man page. Could anybody show me? Thanks.
> 
> I see ARITHMETIC EVALUATION discusses precedence. But I don't think it
> is for [[.

Precedence is basically the same as for arithmetic, && higher than ||
higher than equality and inequality, but you're right that it isn't
explicitly documented in the case of [[.

pws


^ permalink raw reply	[flat|nested] 2+ messages in thread

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2018-12-03 15:14 ` Precedence of operations in [[ Peng Yu
2018-12-03 15:57   ` Peter Stephenson

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