需求：需要對比所有mysql數據庫實例上面的指定參數配置情況，同時需要需要能看到如ip，端口，master or slave，畢竟主和從參數不一樣還是有可能的。

說明：必須要有個數據庫存儲所有是數據庫的信息，如ip，端口，主從關系等，我這裏恰好都滿足，相關敏感信息已脫敏。

#!/bin/bash
#
#call method:sh script_name @@mysql系統參數1,@@mysql系統參數2...[以逗號分隔每個參數]
#

#所有數據庫實例通用的賬號/密碼，比如root/root
user=root
password=root

#存儲元數據的數據庫信息
host=5.5.5.101
port
 
=3306
db=test


mysql -u${user} -p${password} -h${host} ${db} 2>/dev/null -Ns > all.txt<<EOF
 select 
       c.group_name,
       b.cluster_name,
       a.db_ip,
       a.db_port,    
       if(a.is_master = 0, ‘主‘, ‘備‘)
  from db_node a,db_cluster b,db_cluster_group c
  where a.cluster_id=b.id
  
 
and b.group_id=c.id
  and a.status<>‘deleted‘
 order by b.cluster_name;
EOF

 
params=$@
 
cat all |while read line
do
    db_cluster_group=`echo $line | awk ‘{print $1}‘`
    db_cluster_name=`echo $line | awk ‘{print $2}‘`
    db_ip=`echo $line | awk ‘{print $3}‘`
    db_port=`echo $line | awk ‘
 
{print $4}‘`
    db_role=`echo $line | awk ‘{print $5}‘`
    mysql -u${user} -p${password} -h$db_ip -P$db_port 2>/dev/null -Nse "select ‘$db_cluster_group‘,‘$db_cluster_name‘,‘$db_ip‘,‘$db_port‘,‘$db_role‘,$params;"
done

批量獲取mysql數據庫實例指定參數的值