#!/bin/sh

# Extract Period (Month)
extract_period=5
base_date=`date +"%Y-%m-01"`

# Date Generation Loop
for i in `seq ${extract_period} -1 1`
do
  start_date=`date -d "$base_date $i month ago" +"%Y-%m-01T00:00"`

  j=`expr $i - 1`
  end_date=`date -d "$base_date $j month ago" +"%Y-%m-01T00:00"`

  echo $start_date - $end_date
done