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Re: Syntax Question...

From: Greg Wooledge
Subject: Re: Syntax Question...
Date: Wed, 17 Aug 2011 08:32:01 -0400
User-agent: Mutt/

On Tue, Aug 16, 2011 at 02:11:43PM -0700, Linda Walsh wrote:
> 2) His knowledge base about bash seems to be dated or lacking.
> His page on indirect assignment skips using arith expressions and skipped
> one line assignments for assigning to indirect vars using the "<<<" 

It's a wiki, you know.  It can be, and has been, edited by others.  You
could update it yourself.  I very rarely reject any contributions from
others.  If something doesn't work, I'll usually at least attempt to
fix it up rather than reverting it.

> but he totally doesn't talk about
> > b=0
> > a=b
> > (($a=32)
> > echo $b
> 32

imadev:~$ a=b
imadev:~$ (($a=string))
bash: ((: number1 number2 number3 number4: syntax error in expression (error 
token is "number2 number3 number4")


Your trick is limited to numbers.  And not even real numbers, either:

imadev:~$ (($a=2.3))
bash: ((: b=2.3: syntax error: invalid arithmetic operator (error token is ".3")

Just integers.

> >>>>[1]prefix="snapdir/@GMT-"
> >>>>[2]snap_today="$(date +%Y.%m.%d-)"
> >>>>[3]snap_prefix="$mp/$prefix$snap_today*"
> >>>>[4]today_snaps="$('ls' -1 ${snap_prefix} 2>/dev/null |tr "\n" " " )"

Don't store lists in a string.  Store them in an array.


Make sure "set -f" is not in effect, obviously.

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