一、错误日志：
[mysql@host-172-24-115-217 ~]$ service mysql restart
Shutting down MySQL.. SUCCESS!
Starting MySQL..180426 13:36:03 mysqld_safe Logging to ‘/usr/local/mysql/data/alert.log’.
180426 13:36:03 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/data
……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………. ERROR!
二、分析日志：
（1）查看日志
usr/local/mysql/data/alert.log
发现：Version: ‘5.5.59-MariaDB’ socket: ‘/usr/local/mysql/data/mysql.sock’ port: 3306 MariaDB Server
表示mysqld 启动完毕。
（2）查看进程
[mysql@host-172-24-115-217 fd]$ ps -ef | grep mysqld
mysql 20633 1 0 13:36 pts/5 00:00:00 /bin/sh /usr/local/mysql/bin/mysqld_safe –datadir=/usr/local/mysql/data –pid-file=/usr/local/mysql/data/mysqlProcess.pid
mysql 21736 20633 0 13:36 pts/5 00:00:02 /usr/local/mysql/bin/mysqld –basedir=/usr/local/mysql –datadir=/usr/local/mysql/data –plugin-dir=/usr/local/mysql/lib/plugin –log-error=/usr/local/mysql/data/alert.log –pid-file=/usr/local/mysql/data/mysqlProcess.pid –socket=/usr/local/mysql/data/mysql.sock –port=3306
mysql 22436 7333 0 13:40 pts/3 00:00:00 grep mysqld
分析：
从日志和进程信息可以看出此mysqld服务正常。那为什么出现启动失败的现象。
三、挖掘原因
既然mysqld服务进程正常，那从其它机器是否可以登录。经过测试
[mysql@host-172-24-115-218 ~]$ mysql -h272.24.115.217 -uroot -pmysql
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 1
Server version: 5.5.59-MariaDB MariaDB Server
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the current input statement.
MariaDB [(none)]>
经过验证，可以登录。
四：结论
从此可以推断
mysql服务器的client配置错误，导致mysql进程读取配置导致异常
检查/etc/my.cnf 发现如下：
[client]
#socket = /usr/local/mysql/data/mysql.sock
default-character-set = gbk
port = 3306
缺少红色部分，注释后，再次重启一切正常。
希望改进：
希望mysql的启动过程相关的shell脚本也能添加相应的日志，协助分析问题。
That is all.
Good Luck!
