Get the penultimate Wednesday of the month

get_penultimate_wednesday.sh

#!/bin/bash

start_date=$1
end_date=$2
current_date=
counter=0
index=0

until [ "$current_date" = "$end_date" ]
do
    ((counter++))
    current_date=$(date -d "$start_date + $counter days" +%Y%m%d)
    mydate=$(date -d "$start_date + $counter days" +%w)
    if [ $mydate -eq 3 ] ; then
        dates[index]=${current_date}
        ((index++))
    fi
done

array_size=${#dates[@]}

((array_size--))
((array_size--))

echo ${dates[array_size]}