Add 1day one by one with bash.

gistfile1.txt

#!/bin/bash
START_DATE="20150801"
END_DATE="20150826"

echo ${START_DATE};
echo ${END_DATE}

for (( DATE=${START_DATE}; ${DATE} < ${END_DATE}; DATE=`date -d "${DATE} 1 day" '+%Y%m%d'` )) ; do
  echo ${DATE}
  DATE2=`date -d "${DATE}" '+%Y-%m-%d'`
  echo ${DATE2}
done