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Re: evaluating a condition
- X-seq: zsh-users 2599
- From: Sweth Chandramouli <sweth@xxxxxxx>
- To: zsh-users@xxxxxxxxxxxxxx
- Subject: Re: evaluating a condition
- Date: Mon, 13 Sep 1999 12:35:28 -0400
- In-reply-to: <990912235140.ZM23741@xxxxxxxxxxxxxxxxxxxxxxx>
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- References: <Pine.LNX.3.96.990912203255.17690A-100000@xxxxxxxxxxxxxxxxxx> <990912235140.ZM23741@xxxxxxxxxxxxxxxxxxxxxxx>
- Sender: sweth@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Sun, Sep 12, 1999 at 11:51:39PM +0000, Bart Schaefer wrote:
> On Sep 12, 8:41pm, Gaspar Bakos wrote:
> } Subject: evaluating a condition
> }
> } I have the following script, and I would like to print the numbers in the
> } terminal from ${min} to ${max}, if both of them are smaller than 10.
>
> At first I thought you'd found a bug in the math parser, but:
>
> } export min=$3;export max=$4;
> } if (($[min]<10 && $[max]<10)) then
> ^^
> There's a metafied space here. I think zsh is interpreting "\240$[max]" as
> an identifier; e.g. if max=11, the identifier name is "\240\061\061". That
> identifier isn't defined, so it's value is 0 which is always < 10.
??? what?
((...)), at least according to the docs (and as implemented in ksh)
is just another syntax for `let '...''. all the "metafying" (actually,
quoting is unmetafying) does is prevent the shell from interpreting the
space as a word separator; once the string to be evaluated is passed to let,
the space is a space again, and let _should_ (and does, in 3.1.6) simply
ignore it, such that the entire block of code does work.
> } for i in {${min}..${max}}; do echo $i; done
> } fi
>
> This is a danger of permitting identifiers to contain non-ascii characters.
??? okay, what did you do to bart? :)
i assume you meant non-printable and not non-ascii here, though
technically a space is still printable.
one related question that i've long wondered but never about cared
enough to ask: is there a difference between the $[...] and ${...} notations?
-- sweth.
--
Sweth Chandramouli ; <sweth@xxxxxxx>
<a href="http://astaroth.nit.gwu.edu/resume/">Will Work For Food.</a>
<a href="http://astaroth.nit.gwu.edu/~sweth/disc.html">*</a>
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