1，昨天看到shell一道面试题，需求如下：
监控MySQL主从同步是否异常，如果异常，则发送短信或者邮件给管理员。提示：如果没主从同步环境,可以用下面文本放到文件里读取来模拟：
阶段1：开发一个守护进程脚本每30秒实现检测一次。
阶段2：如果同步出现如下错误号(1158,1159,1008,1007,1062)，则跳过错误。
阶段3：请使用数组技术实现上述脚本(获取主从判断及错误号部分)
[root@oldboy~]# mysql -uroot -p'oldboy' -S /data/3307/mysql.sock -e "show slavestatus\G;"
*************************** 1. row ***************************
Slave_IO_State:Waiting for master to send event
Master_Host:10.0.0.179 #当前的mysql master服务器主机
Master_User: rep
Master_Port: 3306
Connect_Retry: 60
Master_Log_File:mysql-bin.000013
Read_Master_Log_Pos: 502547
Relay_Log_File:relay-bin.000013
Relay_Log_Pos:251
Relay_Master_Log_File:mysql-bin.000013
Slave_IO_Running:Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB: mysql
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 502547
Relay_Log_Space:502986
Until_Condition:None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0 #和主库比同步延迟的秒数，这个参数很重要
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
2，好久没写过脚本，所以就写了一个，如果各位看观发现有问题，还请指教，谢谢!
#!/bin/bash
#author:linsir
#qq:384108391
#检查mysql同步情况
#定义初始变量
mysql_sync_status=/tmp/mysql_sync_status.txt
error_log=/tmp/mysql_sync_error.txt
user=root
passwd=linlin
CMD="/usr/local/mysql2/bin/mysql -S /tmp/3307.sock -u$user -p$passwd -e"
mail_address='384108391@'
time=`date +%F-%T`
ip=`ifconfig eth0|awk -F '[ :]+' '{print $4}'|awk "{if(NR==2) print}"`
errorcode=(1158 1159 1008 1007 1062)
#mysql主从同步会出现错误代码1158 1159 1008 1007 1062，这些错误代码不会对主从同步影响非常大。所以如果遇到这个错误代码，就到下个需要执行的sql即可
#检查mysql status中的Last_Errno的值，正常一般为0.
Continue_errorcode() {
$CMD "show slave status\G" > $mysql_sync_status 2>/dev/null
code=`awk '/Last_Errno/ {print $2}' $mysql_sync_status`
if [ "$code" != "0" ];then
for ccode in ${errorcode[*]}
do
if [ "$code" = "$ccode" ];then
$CMD "stop slave;set global sql_slave_skip_counter = 1;start slave;" 2>/dev/null
$CMD "show slave status\G" > $mysql_sync_status 2>/dev/null
flag=1 && break
fi
done
else
flag=1
fi
}
Check_ok() {
IO=`awk '/Slave_IO_Running/ {print $2}' $mysql_sync_status`
SQL=`awk '/Slave_SQL_Running:/ {print $2}' $mysql_sync_status`
# echo $IO
# echo $SQL
if [ "$IO" = "No" -o "$SQL" = "No" ];then
Error_format "$time" "$ip" "mysql同步失败，IO或SQL线程down"
fi
}
Delay_time() {
t=`awk '/Seconds_Behind_Master/ {print $2}' $mysql_sync_status`
if [ "$t" = "NULL" ] ;then
Error_format "$time" "$ip" "mysql同步出错，Seconds_Behind_Master is NUll"
else
if [ $t -gt 0 ];then
Error_format "$time" "$ip" "mysql同步超时，超时时间为$t"
fi
fi
}
Error_format() {
echo "
Mysql master-slave synchronization state
----------------------------------------------------------
time: $1
host: $2
question: $3
----------------------------------------------------------
" >> $error_log
}
main() {
while true
do
cat /dev/null >$error_log
Continue_errorcode
if [ "$flag" != "1" ];then
Error_format "$time" "$ip" "mysql同步出错，错误代码:$code"
fi
Check_ok
Delay_time
[ `cat $error_log|wc -l` -ne 0 ] && mail -s 'mysql同步异常,请及时处理' -a $mysql_sync_status $mail_address < $error_log
sleep 30
done
}
main
