第一个问题：

root@b-ThinkPad-X230s:/usr/local/mysql/bin# ./mysqld_safe start   (开启mysql的服务！)

151123 14:19:04 mysqld_safe Logging to '/usr/local/mysql/data/b-ThinkPad-X230s.err'.

151123 14:19:04 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/data

151123 14:19:05 mysqld_safe mysqld from pid file /usr/local/mysql/data/b-ThinkPad-X230s.pid ended

root@b-ThinkPad-X230s:/usr/local/mysql/bin# ./mysql --user=mysql   (使用mysql用户登录)

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)  (报错！)

以为是用户的问题，然后尝试换一个用户名：

root@b-ThinkPad-X230s:/usr/local/mysql/bin# ./mysql -u root         (使用root用户登录)

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)  (报错！)

然后想着是否是没有用户设置密码的问题，因为貌似是不用密码也可以登录的，先尝试设置密码：

root@b-ThinkPad-X230s:/usr/local/mysql/bin# ./mysqladmin -u mysql password "123456"

./mysqladmin: connect to server at 'localhost' failed

error: 'Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)'

Check that mysqld is running and that the socket: '/tmp/mysql.sock' exists!

查看服务是否已经启动：

root@b-ThinkPad-X230s:/tmp# ps -aux | grep "mysql"

root      4518  0.0  0.0  13708  2296 pts/11   S+   14:35   0:00 grep --color=auto mysql       (没有启动mysql服务)

已经尝试遍了网上搜寻的所有解决办法，最后按照同事的提示，重新编译安装吧，然后重新编译安装！

然后就通过了，可以正常登录！比较无语！