How to configure nginx log scheduled backup and deletion

#!/bin/bash
#auth:lzq
#desc:把当前日志按日期备份，重新生成第二天的日志文件
#date:2016-09-18

date=`date +%y%m%d`
nginx_pid=`cat /var/run/nginx.pid`
#如果当前nginx没有运行就退出
if [ "$?" != 0 ]
then
    exit 1;
fi

#nginx 日志所在的路径
log_path='/usr/local/nginx/logs/'
log_name='access.log'
mv ${log_path}${log_name} ${log_path}${log_name}$date

#删除7天前旧的备份文件
function deloldbak()
{
    olddate=`date +"%y%m%d" -d "-$1 day"`
    if [ -e "${log_path}${log_name}$olddate" ]
    then
        rm -f ${log_path}${log_name}$olddate
        echo "${log_path}${log_name}$olddate del ok"
    fi
}

#重载nginx配置，重新生成nginx日志文件
kill -usr1 $nginx_pid

if [ "$?" == 0 ]
then
    deloldbak 7
    exit 0;
fi