xampp in ubuntu下命令行启动mysql报错：

reddevil@reddevil-Lenovo:/opt/lampp$ ./bin/mysql -u root -p
Enter password: 
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/opt/lampp/var/mysql/mysql.sock' (2)

启动mysql服务：

reddevil@reddevil-Lenovo:/opt/lampp$ /opt/lampp/lampp start
You need to start XAMPP as root!
reddevil@reddevil-Lenovo:/opt/lampp$ su root
Password: 
root@reddevil-Lenovo:/opt/lampp# /opt/lampp/lampp start
Starting XAMPP for Linux 1.7.7...
XAMPP: Starting Apache with SSL (and PHP5)...
XAMPP: Starting MySQL...
XAMPP: Starting ProFTPD...
XAMPP for Linux started.

运行mysqlStart.sh：

#!/bin/bash
sudo rm -rf /var/run/mysqld
sudo mkdir /var/run/mysqld
sudo ln -s /opt/lampp/var/mysql/mysql.sock /var/run/mysqld/mysql.sock

关于此这篇文章给出很好的分析：http://www.samundra.com.np/solved-error-2002-hy000-cant-connect-to-local-mysql-server-through-socket-varrunmysqldmysqld-sock-2/563

命令行启动mysql

reddevil@reddevil-Lenovo:/opt/lampp$ ls
bin      error  htdocs  lampp  libexec   logs     phpmyadmin    sbin   tmp
cgi-bin  etc    icons   lib    licenses  modules  RELEASENOTES  share  var
reddevil@reddevil-Lenovo:/opt/lampp$ /bin/mysql -u root -p
bash: /bin/mysql: No such file or directory
reddevil@reddevil-Lenovo:/opt/lampp$ ./bin/mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.5.16 Source distribution

Copyright (c) 2000, 2011, 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.

mysql> 

至此，问题解决