The underlying problem is: arrays in bash (and ksh88 as well) are ONE-dimensional. Therefore, you can create a variable holding a one-dimensional array, but you can't put other array variables as elements into this array.

You could use the following workaround, but i strongly suggest you don't. Stretching the limits of what can be done is fun and helps learning the trade, but you shouldn't put circus tricks into production code. So, with this (rather big) grain of salt, here it goes:

Variables are evaluated always in the same step and all at the same time, which is why you cannot do things like this:

Code:

xfoo="abc"
yfoo="def"
selector="x"

echo ${${selector}foo}

This would rely on "${selector}" to be evaluated first and only then the resulting "${xfoo}" to be evaluated again. But, as i said, this is not the case and therefore this will fail.

There is one remedy for that, though: the keyword eval. eval starts the evaluation process again and this way you get (among other things) a second evaluation phase for your variables:

Code:

xfoo="abc"
yfoo="def"
selector="x"

eval echo \${${selector}foo}

The same way you can create sort-of two-dimensional arrays by using this mechanism:

Code:

arr1[1]="arr1.1"
arr1[2]="arr1.2"
arr1[3]="arr1.3"
arr1[4]="arr1.4"

arr2[1]="arr2.1"
arr2[2]="arr2.2"
arr2[3]="arr2.3"
arr2[4]="arr2.4"

arr3[1]="arr3.1"
arr3[2]="arr3.2"
arr3[3]="arr3.3"
arr3[4]="arr3.4"


for i in 1 2 3 ; do
     for j in 1 2 3 4 ; do
         eval echo \${arr${i}[$j]}
     done
done

But again: avoid eval like the plague and if you have to use it this is usually indicative that you better search for an alternative. As a show-off of skill, though, it is pretty cool. No?

I hope this helps.

bakunin