用XAMPP装装好mysql之后，mysql -uroot 连不上，报这个错误：
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock'
在mysql的配置文件里，/opt/lampp/etc/my.cnf， 发现了这样的配置：
[java]
# The following options will be passed to all MySQL clients
[client]
#password = your_password
port = 3306
socket = /opt/lampp/var/mysql/mysql.sock
# Here follows entries for some specific programs
# The MySQL server
[mysqld]
user = nobody
port = 3306
socket = /opt/lampp/var/mysql/mysql.sock
# The following options will be passed to all MySQL clients
[client]
#password = your_password
port = 3306
socket = /opt/lampp/var/mysql/mysql.sock
# Here follows entries for some specific programs
# The MySQL server
[mysqld]
user = nobody
port = 3306
socket = /opt/lampp/var/mysql/mysql.sock
原来mysql用的套接字文件是：/opt/lampp/var/mysql/mysql.sock于是建立了个软连接， 命令如下。不能建立硬链接，不知道为什么。
ln -s /opt/lampp/var/mysql/mysql.sock /var/run/mysqld/mysqld.sock
现在可以用mysql -uroot命令登陆上了~