Variable as bash array index?

Question

#!/bin/bash  set -x  array_counter=0 array_value=1  array=(0 0 0)  for number in ${array[@]} do     array[$array_counter]="$array_value"     array_counter=$(($array_counter + 1)) done 

When running above script I get the following debug output:

+ array_counter=0 + array_value=1 + array=(0 0 0) + for number in '${array[@]}' + array[$array_counter]=1 + array_counter=1 + for number in '${array[@]}' + array[$array_counter]=1 + array_counter=2 + for number in '${array[@]}' + array[$array_counter]=1 + array_counter=3 

Why does the variable $array_counter not expand when used as index in array[]?

Answer 1

Bash seems perfectly happy with variables as array indexes:

$ array=(a b c) $ arrayindex=2 $ echo ${array[$arrayindex]} c $ array[$arrayindex]=MONKEY $ echo ${array[$arrayindex]} MONKEY