#!/bin/bash

#-------------------------------------------------------------------------------
# Example 2 for Bash Tips show 19: the mapfile/readarray command
#-------------------------------------------------------------------------------

#
# Declare an indexed array
#
declare -a map

#
# Fill the array with a process substitution that generates 10 random numbers,
# each followed by a newline (the default delimiter). We remove the newline
# characters.
#
mapfile -t map < <(for i in {1..10}; do echo $RANDOM; done)

#
# Show the array as a list
#
echo "map: ${map[*]}"
echo

#
# Declare a new indexed array
#
declare -a daffs

#
# Define a string with spaces replaced by underscores
#
words="I_wandered_lonely_as_a_Cloud_That_floats_on_high_o'er_vales_and_Hills,_When_all_at_once_I_saw_a_crowd,_A_host,_of_golden_Daffodils"

#
# Fill the array with a process substitution that provides the string. The
# delimiter is '_' and we remove it as we load the array
#
mapfile -d _ -t daffs < <(echo -n "$words")

#
# Show the array as a list
#
echo "daffs: ${daffs[*]}"
echo

#
# Fill an array with 100 random dictionary words. Use 'printf' as the callback
# to report every 10th word using -C and -c
#
declare -a big
mapfile -t -C "printf '%02d %s\n' " -c 10 big < <(grep -E -v "'s$" /usr/share/dict/words | shuf -n 100)
echo

#
# Report every 10th element of the populated array in the same way
#
echo "big: ${#big[*]} elements"
for ((i = 9; i < ${#big[*]}; i=i+10)); do
    printf '%02d %s\n' "$i" "${big[$i]}"
done

exit