#!/bin/bash

#-------------------------------------------------------------------------------
# Example 4 for Bash Tips show 17: Using "substring expansion" to extract
# associative array elements
#-------------------------------------------------------------------------------

#
# Make two indexed arrays each containing 6 random words. Note: this is not
# the best way to do this!
#
declare -a a1=( $(for word in $(grep -E -v "'s$" /usr/share/dict/words | shuf -n 6); do echo $word; done) )
declare -a a2=( $(for word in $(grep -E -v "'s$" /usr/share/dict/words | shuf -n 6); do echo $word; done) )

#
# Build an associative array using one set of words as subscripts and the
# other as the values
#
declare -A hash
for ((i=0; i<6; i++)); do
    hash[${a1[$i]}]="${a2[$i]}"
done

#
# Display the associative array contents
#
echo "Contents of associative array 'hash'"
for key in "${!hash[@]}"; do
    printf '%s=%s\n' "hash[$key]" "${hash[$key]}"
done
echo

#
# Walk the associative array printing pairs of values
#
echo "Pairs of values from array 'hash'"
for ((i=1; i<6; i+=2)); do
    printf '%d: %s\n' "$i" "${hash[*]:$i:2}"
done