how to use variable substitudes as array names

Question

suppose I have 2 arrays:

A=(a1 a2 a3)
B=(b1 b2 b3)

I want to display contents of A and B with a loop, something like this:

for i in A B
do
    echo ${${i}[@]}
done

and get results like this

a1 a2 a3
b1 b2 b3

how can I realize this?

chepner · Accepted Answer · 2016-12-11 16:08:12Z

2

Use indirect parameter expansion.

for i in A B; do
  t="$i[@]"   # A[@] or B[@]
  echo "${!t}"
done

The trick is to treat the array name plus the index ([@]) together as a variable "name".

answered Dec 11, 2016 at 16:08

chepner

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