Indirect reference to array values in bash

Question

I am trying to do an indirect reference to values in an array in bash.

anotherArray=(\"foo\" \"faa\")

foo=(\"bar\" \"baz\")
faa=(\"test1\" \"test2\")


for          


        

Answer 1

Modern versions of bash adopt a ksh feature, "namevars", that's a perfect fit for this issue:

#!/usr/bin/env bash
case $BASH_VERSION in ''|[123].*|4.[012]) echo "ERROR: Bash 4.3+ needed" >&2; exit 1;; esac

anotherArray=("foo" "faa")

foo=("bar" "baz")
faa=("test1" "test2")

for indirectName in "${anotherArray[@]}"; do
  declare -n indirect="$indirectName"
  echo "${indirect[0]}"
  echo "${indirect[1]}"
done

Answer 2

You need do it in two steps

$ for i in ${anotherArray[@]}; do 
     t1=$i[0]; t2=$i[1]; 
     echo ${!t1} ${!t2};  
  done

bar baz
test1 test2

Answer 3

You have to write the index in the variable used for indirection :

anotherArray=("foo" "faa")
foo=("bar" "baz")
faa=("test1" "test2")

for indirect in ${anotherArray[@]}; do
  all_elems_indirection="${indirect}[@]"
  second_elem_indirection="${indirect}[1]"
  echo ${!all_elems_indirection}
  echo ${!second_elem_indirection}
done

If you want to iterate over every element of every arrays referenced in anotherArray, do the following :

anotherArray=("foo" "faa")
foo=("bar" "baz")
faa=("test1" "test2")

for arrayName in ${anotherArray[@]}; do
  all_elems_indirection="${arrayName}[@]"
  for element in ${!all_elems_indirection}; do
    echo $element;
  done
done

Alternatively you could directly store the whole indirections in your first array : anotherArray=("foo[@]" "faa[@]")