mysql 不能登录

[root@localhost  ~]# mysql -uroot -p
Enter password:
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (111)

1解决方案：

1.1

[root@localhost  ~]# service mysql start    ###重启数据库
Starting MySQL                                             [  OK  ]
[root@localhost  ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.5.32-log Source distribution

Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

2.如若出现下面的error

[root@localhost mysql]# /etc/rc.d/init.d/mysql status
MySQL is not running, but lock file (/var/lock/subsys/mysql[FAILED]
[root@localhost mysql]# /etc/rc.d/init.d/mysql start
Starting MySQL...The server quit without updating PID file (/usr/local/mysql/data/localhost.localdomain.pid).                             [FAILED]

2.1解决方案

[root@localhost ~]# cd /usr/local/mysql

[root@localhost mysql]# chown -R mysql.mysql .
[root@localhost mysql]# su - mysql
[mysql@localhost ~]$ cd /usr/local/mysql
[mysql@localhost mysql]$scripts/mysql_install_db
Installing MySQL system tables...
OK
Filling help tables...
OK

To start mysqld at boot time you have to copy
support-files/mysql.server to the right place for your system

PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER !
To do so, start the server, then issue the following commands:

./bin/mysqladmin -u root password 'new-password'
./bin/mysqladmin -u root -h localhost.localdomain password 'new-password'

Alternatively you can run:
./bin/mysql_secure_installation

which will also give you the option of removing the test
databases and anonymous user created by default. This is
strongly recommended for production servers.

See the manual for more instructions.

You can start the MySQL daemon with:
cd . ; ./bin/mysqld_safe &

You can test the MySQL daemon with mysql-test-run.pl
cd ./mysql-test ; perl mysql-test-run.pl

Please report any problems with the ./bin/mysqlbug script!

[mysql@localhost] cd  /usr/local/mysql/bin ,

[mysql@localhost] ./mysqld_safe --user=mysql &  

[mysql@localhost] ./mysql -u root  -p 

此时系统会提示你输入密码，刚安装好后， 默认密码为空，你直接 回车  即可。如果你的安装没有问题，应该能成功。