Bash iterate through multiple arrays

Question

I have defined multiple arrays:

array1=(el1 el2 el3 el4 el5)
array2=(el10 el12 el14)
array3=(el5 el4 el11 el8)

I need to iterate through all elements of all arrays. The following is the syntax I use:

for j in {1..3}
do
    for (( k = 0 ; k < ${#array$j[*]} ; k++ ))
    do
        #perform actions on array elements, refer to array elements as "${array$j[$k]}"
    done
done

However, the above snippet fails with the message(s)

k < ${#array$j[*]} : bad substitution and 
${array$j[$k]}: bad substitution

What is wrong with my array syntax?

Answer 1

Your script is not correct.

1. First of all there should not be comma separating various elements in your 3 arrays.
2. Then to use array name as variable you need to use indirection

Following should work:

array1=(el1 el2 el3 el4 el5)
array2=(el10 el12 el14)
array3=(el5 el4 el11 el8)

for j in {1..3}
do
    n="array$j[@]"
    arr=("${!n}")
    for (( k = 0 ; k < ${#arr[@]} ; k++ ))
    do
        #perform actions on array elements, refer to array elements as "${array$j[$k]}"
        echo "Processing: ${arr[$k]}"
    done
done

This will process all 3 arrays and gives this output:

Processing: el1
Processing: el2
Processing: el3
Processing: el4
Processing: el5
Processing: el10
Processing: el12
Processing: el14
Processing: el5
Processing: el4
Processing: el11
Processing: el8

Answer 2

This:

array1=(el1 el2 el3 el4 el5)
array2=(el10 el12 el14)
array3=(el5 el4 el11 el8)

for j in {1..3} ; do
    # copy array$j to a new array called tmp_array:
    tmp_array_name="array$j[@]"
    tmp_array=("${!tmp_array_name}")

    # iterate over the keys of tmp_array:
    for k in "${!tmp_array[@]}" ; do
        echo "\${array$j[$k]} is ${tmp_array[k]}"
    done
done

prints this:

${array1[0]} is el1
${array1[1]} is el2
${array1[2]} is el3
${array1[3]} is el4
${array1[4]} is el5
${array2[0]} is el10
${array2[1]} is el12
${array2[2]} is el14
${array3[0]} is el5
${array3[1]} is el4
${array3[2]} is el11
${array3[3]} is el8

There may well be some way to do this without creating tmp_array, but I couldn't get the indirection to work without it.