1，昨天看到shell一道面試題，需求如下：

監控MySQL主從同步是否異常，如果異常，則發送短信或者郵件給管理員。提示：如果沒主從同步環境,可以用下面文本放到文件裏讀取來模擬：
階段1：開發一個守護進程腳本每30秒實現檢測一次。
階段2：如果同步出現如下錯誤號（1158,1159,1008,1007,1062），則跳過錯誤。
階段3：請使用數組技術實現上述腳本（獲取主從判斷及錯誤號部分）

[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   #當前的mysql master服務器主機
                  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   #和主庫比同步延遲的秒數，這個參數很重要
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error: 
               Last_SQL_Errno: 0
               Last_SQL_Error:

2，好久沒寫過腳本，所以就寫了一個，如果各位看觀發現有問題，還請指教，謝謝!

#!/bin/bash
#author:linsir
#qq:384108391
#檢查mysql同步情況

#定義初始變量
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=‘[email protected]‘

time=`date +%F-%T`
ip=`ifconfig eth0|awk  -F ‘[ :]+‘ ‘{print $4}‘|awk "{if(NR==2) print}"`
errorcode=(1158 1159 1008 1007 1062)


#mysql主從同步會出現錯誤代碼1158 1159 1008 1007 1062，這些錯誤代碼不會對主從同步影響非常大。所以如果遇到這個錯誤代碼，就到下個需要執行的sql即可
#檢查mysql status中的Last_Errno的值，正常一般為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同步失敗，IO或SQL線程down"
      fi
}


Delay_time() {
	t=`awk ‘/Seconds_Behind_Master/ {print $2}‘ $mysql_sync_status`
        if [ "$t" = "NULL" ] ;then
        Error_format "$time" "$ip" "mysql同步出錯，Seconds_Behind_Master is NUll"
	else
           if [ $t -gt  0 ];then
             Error_format "$time" "$ip" "mysql同步超時，超時時間為$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同步出錯，錯誤代碼:$code"
      fi
      Check_ok
      Delay_time
      [ `cat $error_log|wc -l` -ne 0 ] && mail -s  ‘mysql同步異常,請及時處理‘  -a $mysql_sync_status $mail_address < $error_log
      sleep 30
  done
}



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監控mysql主從同步