How to make 3D array in BASH?

Question

I want to write/make/use a 3D array of [m][n][k] in BASH. From what I understand, BASH does not support array that are not 1D.

Any ideas how to do it?

Answer 1

Fake multi-dimensionality with a crafted associative array key:

declare -A ary
for i in 1 2 3; do 
    for j in 4 5 6; do 
        for k in 7 8 9; do 
            ary["$i,$j,$k"]=$((i*j*k))
        done
    done
done
for key in "${!ary[@]}"; do printf "%s\t%d\n" "$key" "${ary[$key]}"; done | sort

1,4,7   28
1,4,8   32
1,4,9   36
1,5,7   35
1,5,8   40
1,5,9   45
1,6,7   42
1,6,8   48
1,6,9   54
2,4,7   56
2,4,8   64
2,4,9   72
2,5,7   70
2,5,8   80
2,5,9   90
2,6,7   84
2,6,8   96
2,6,9   108
3,4,7   84
3,4,8   96
3,4,9   108
3,5,7   105
3,5,8   120
3,5,9   135
3,6,7   126
3,6,8   144
3,6,9   162

I used sort because keys of an assoc.array have no inherent order.

Answer 2

You can use associative arrays if your bash is recent enough:

unset assoc
declare -A assoc
assoc["1.2.3"]=x

But, I'd rather switch to a language that supports multidimensional arrays (e.g. Perl).