此腳本首先判斷mysql服務器是否運行，如果正常，繼續判斷主從，否則發郵件告警,只發一次。
判斷主從狀態是判斷IO和SQL線程是否都為yes，如果不是則發郵件通知，只發一次。

代碼如下:
#!/bin/bash
#define mysql variable
mysql_user="root"
mysql_pass="123456"
email_addr="slave@jb51.net"

mysql_status=`netstat -nl | awk 'NR>2{if ($4 ~ /.*:3306/) {print "Yes";exit 0}}'`
if [ "$mysql_status" == "Yes" ];then
        slave_status=`mysql -u${mysql_user} -p${mysql_pass} -e"show slave status/G" | grep "Running" | awk '{if ($2 != "Yes") {print "No";exit 1}}'`
        if [ "$slave_status" == "No" ];then
                echo "slave is not working!"
                [ ! -f "/tmp/slave" ] && echo "Slave is not working!" | mail -s "Warn!MySQL Slave is not working" ${email_addr}
                touch /tmp/slave
        else
                echo "slave is working."
                [ -f "/tmp/slave" ] && rm -f /tmp/slave
        fi
        [ -f "/tmp/mysql_down" ] && rm -f /tmp/mysql_down
else
        [ ! -f "/tmp/mysql_down" ] && echo "Mysql Server is down!" | mail -s "Warn!MySQL server is down!" ${email_addr}
        touch /tmp/mysql_down
fi