Hash tables (associative arrays) in linux shell scripts

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Hash tables (associative arrays) in linux shell scripts

bash

bash v3

function key_val () {
    case $1 in
        "foo") echo "bar";;
        "baz") echo "qux";;
        *) echo "default";;
    esac
}

for key in "foo" "baz"; do
    echo "$key: $(key_val $key)"
done

bash v4

declare -A arr
arr=([foo]=bar [baz]=qux)

for key in ${!arr[@]}; do 
    echo "$key: ${arr[$key]}"
done

zsh

declare -A arr
arr=([foo]=bar [baz]=qux)

for key value in ${(kv)arr}; do 
    echo "$key: $value"
done

Hacky cross-shell alternative

#!/bin/bash

arr=(
    "key value"
    "foo bar"
)

for item in "${arr[@]}"; do
    key=$(echo $item | cut -d " " -f 1)
    value=$(echo $item | cut -d " " -f 2)
    
    echo "$key: $value"
done