备份数据库，并删除七日之前的备份，只保留七日之内的备份数据。

#!/bin/bash
 
db_user="user"
db_pwd="password"
 
for db in "db1" "db2"
do
    cd "/backup/path/${db}"
    mysqldump -u ${db_user} -p${db_pwd} ${db} | gzip > "${db}.`date -d "now" +%Y%m%d`.sql.gz"
    rm -f "${db}.`date -d "-7 days" +%Y%m%d`.sql.gz"
done