>>673
bash、GNU date依存

#!/bin/bash

while getopts s:e: opt; do
case "${opt}" in
's') stime=$(date -d "${OPTARG}" '+%s') ;;
'e') etime=$(date -d "${OPTARG}" '+%s') ;;
esac
done

t=${stime}

while (( ${etime} >= ${t} )); do
date -d @${t} '+%Y%m%d'
t=$(( ${t} + (60 * 60 * 24) ))
done