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
mysql206331 0 13:36 pts/500:00:00 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/usr/local/mysql/data --pid-file=/usr/local/mysql/data/mysqlProcess.pid
mysql21736 20633 0 13:36 pts/500:00:02 /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
mysql22436 7333 0 13:40 pts/300:00:00 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!