Re: Docco

[Andreas Schwab]

On Mär 27 2024, Greg Wooledge wrote:

>> $ [ ! -a /tmp ] && echo ok || echo nok
>> ok
>
> Here, you have three arguments, and argument 2 is a "binary primary"
> (POSIX wording again), so it's treated as if you had written this:
>
>     [ ! ] && [ /tmp ] && echo ok || echo nok
>
> This is simply performing two string length tests.  Both strings are
> non-empty (the first is one character, and the second is four), so
> the result is true.
>
> The check for whether the first argument is '!' is not performed,
> because the "$2 is a binary primary" check comes first.  This is how
> POSIX documents it.

FWIW, ksh parses it the other way round:

$ ksh93 -c '[ ! -a /tmp ]; echo $?; [ . -a /tmp ]; echo $?; [ - -a /tmp ]; echo 
$?' 
1
0
ksh93: [: -: unknown operator
2

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
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"And now for something completely different."