场景:整库备份，用exp方式，按周循环，备份文件存在oracle下的db_backup目录，周一备份到成dbbackup_1.dmp，周二：dbbackup_2.dmp，周三：dbbackup_3.dmp，周四：dbbackup_4.dmp，周五：dbbackup_5.dmp，周六：dbbackup_6.dmp，周日：dbbackup_7.dmp，并且循环覆盖，服务器上只存7个备份文件 

shell脚本：dbback.sh

#!/bin/sh

day=`date +%w`
if [ ${day} == "0" ]; then
  day="7"
fi
bakfile=/home/oracle/db_backup/dbbackup_${day}.dmp

exp userid=system/manager file=${bakfile} full=yes

定期备份数据库数据