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Re: [Help-bash] indirection for arrays

From: Dan Douglas
Subject: Re: [Help-bash] indirection for arrays
Date: Wed, 09 May 2012 02:42:34 -0500
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On Monday, May 07, 2012 08:22:51 AM Greg Wooledge wrote:
> On Sat, May 05, 2012 at 02:16:36PM -0600, Bill Gradwohl wrote:
> > Via a web site reference, Dan Douglas (Thank You) provided something akin
> > to this:
> > 
> > func() {
> > 
> >     local -a 'keys=("${!'"$1"'address@hidden")'
> It burns!!
> > declare -a myArray=(1 2 3)
> > 
> > func 'myArray'
> For the love of god, if you want to pass arrays to a function by name,
> use ksh93, not bash.

Good advice. (unfortunately not always an option).

> UNTIL SUCH TIME as bash has a feature like this, you cannot do this in
> bash.  Throwing dozens of random punctuation characters at the screen
> until the code appears to do what you think it should do is not sane.

Not random. The same behavior affects this more common construct:

 ~ $ x=y; y=(1 2 3); declare -a "$x"+=(a b c); declare -p y
-bash: syntax error near unexpected token `('

One would need to know that this triggers declare to treat args as ordinary
args and to quote the entire thing as such.

And it isn't limited to declare - eval does it too:

 $ eval x=(1 2 3); declare -p x
declare -a x='([0]="1" [1]="2" [2]="3")'

But this might be a bug since presumably eval always takes ordinary arguments,
and ignores the metacharacters in this special case for some reason.
Dan Douglas

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