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Re: Parameter expansion

X-seq: zsh-users 2337
From: Peter Stephenson <pws@xxxxxxxxxxxxxxxxx>
To: zsh-users@xxxxxxxxxxxxxx
Subject: Re: Parameter expansion
Date: Mon, 17 May 1999 11:23:22 +0200
In-reply-to: "Roland Jesse"'s message of "Mon, 17 May 1999 11:39:18 DFT." <14143.58310.693584.42423@xxxxxxxxxxxxxxxxxxxxxxxxx>
Mailing-list: contact zsh-users-help@xxxxxxxxxxxxxx; run by ezmlm

Roland Jesse wrote:
> But why do I do get the following than?
> 
> % if [ ! ${+BLURB} ]; then
> then> echo "BLURB not set"
> then> else
> else> echo "BLURB set"
> else> fi
> BLURB set
> % 

That's becuase

% if [ ! 0 ]; then print no; else print yes; fi
yes
% if [ ! 1 ]; then print no; else print yes; fi
yes

It's testing whether the string has length zero, which it doesn't.  You
need arithmetical evaluation; change the [ to (( and the ] to )) and
everything should work.

-- 
Peter Stephenson <pws@xxxxxxxxxxxxxxxxx>       Tel: +39 050 844536
WWW:  http://www.ifh.de/~pws/
Dipartimento di Fisica, Via Buonarroti 2, 56127 Pisa, Italy

References:
- Parameter expansion
  - From: Roland Jesse

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