From: Kurtis Rader <krader@skepticism.us>
To: Thorsten Kampe <thorsten@thorstenkampe.de>
Cc: Zsh Users <zsh-users@zsh.org>
Subject: Re: `[[ -n $VAR ]]` equal to `[[ $VAR ]]`?
Date: Thu, 9 Apr 2015 19:05:59 -0700 [thread overview]
Message-ID: <CABx2=D93rJDoqGHa=9=nGZZU=9oC_vc-0FHE8ZERV9LmxtqRaA@mail.gmail.com> (raw)
In-Reply-To: <CABx2=D9Mk01ovQkMyWT_1nh9WdDvcpqmMJAOdka-oEmN8Xe4nw@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 1518 bytes --]
Bart's reply explains why I get a parse error: Mac OS X still has zsh
v5.0.5 which does not support the bash semantics for a bare string inside
[[ ]]. Even if you don't need compatibility with pre v5.0.6 zsh releases I
would discourage that syntax because of its ambiguity.
On Thu, Apr 9, 2015 at 7:02 PM, Kurtis Rader <krader@skepticism.us> wrote:
> Okay, I had forgotten that a bare string is equivalent to "-n string" in
> bash. The zsh documentation makes no mention of this "feature". It probably
> works for you and not me because of an option that differs between our two
> environments. Although for the life of me I can't figure out what that
> option is.
>
> On Thu, Apr 9, 2015 at 6:39 PM, Thorsten Kampe <thorsten@thorstenkampe.de>
> wrote:
>
>> * Kurtis Rader (Thu, 9 Apr 2015 18:31:04 -0700)
>> > When I run the following
>> >
>> > [[ $VAR ]] && print yes
>> >
>> > I get a parse error. Which is what I expected given the documentation in
>> > section "Conditional Expressions" of "man zshall". Are you seeing
>> different
>> > behavior? What makes you think a bare variable is a valid expression?
>>
>>
>> ```
>> VAR=
>>
>> if [[ $VAR ]]
>> then
>> printf "something\n"
>> else
>> printf "nothing\n"
>> fi
>> ```
>>
>> Works fine in zsh and bash.
>>
>> Same goes for
>> `[[ $VAR ]] && printf "something\n" || printf "nothing\n"`
>>
>>
>
>
> --
> Kurtis Rader
> Caretaker of the exceptional canines Junior and Hank
>
--
Kurtis Rader
Caretaker of the exceptional canines Junior and Hank
next prev parent reply other threads:[~2015-04-10 2:06 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-10 1:23 Thorsten Kampe
2015-04-10 1:31 ` Kurtis Rader
2015-04-10 1:39 ` Thorsten Kampe
2015-04-10 2:02 ` Kurtis Rader
2015-04-10 2:05 ` Kurtis Rader [this message]
2015-04-10 2:46 ` Mikael Magnusson
2015-04-10 2:59 ` Kurtis Rader
2015-04-10 4:00 ` Mikael Magnusson
2015-04-10 6:06 ` Thorsten Kampe
2015-04-13 16:52 ` Ray Andrews
2015-04-13 17:36 ` Roman Neuhauser
2015-04-13 23:58 ` Ray Andrews
2015-04-14 1:27 ` Bart Schaefer
2015-04-14 15:06 ` Ray Andrews
2015-04-10 3:21 ` Kurtis Rader
2015-04-10 2:01 ` Bart Schaefer
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