Accessing array index variable from bash shell script loop?

Question

I want to access the array index variable while looping thru an array in my bash shell script.

myscript.sh

#!/bin/bash
A=('foo' 'bar' 'baz' 'bat')
for i in ${A[*]}; do
  echo $i
done

Actual result

foo
bar
baz
bat

Desired result

0
1
2
3

How do I alter my script to achieve this?

Answer 1

You can loop over index using indirect reference syntax (since Bash 3) :

#!/bin/bash

A=('foo' 'bar' 'baz' 'bat')
for i in ${!A[*]}; do # replace ${A[*]} with ${!A[*]}
  echo $i
done

For more : How to iterate over associative arrays in Bash