bash脚本打印时间段

#!/bin/sh
beg_date=`date -d "$1" +%s`
end_date=`date -d "$2" +%s`

if [[ -z $1 ]]||[[ -z $2 ]];then
        echo "Usage: $0 YYYY-MM-DD YYYY-MM-DD"
        exit 0;
fi
if [[ ${beg_date} > ${end_date} ]];then
        echo "The end_date < beg_date ;Please input the right date,example: $0 2014-01-01 2014-03-01"
        exit 0;
fi

for (( i=${beg_date};i<=${end_date};i=i+86400))
do
        d=`date -d "1970-1-1 UTC $i seconds" +%Y%m%d`
	echo $d
done