启动mysql时报错：
Starting mysqld daemon with databases from /var/lib/mysql
STOPPING server from pid file /var/run/mysqld/mysqld.pid
071112 00:22:06 mysqld ended
查看日志：
＃less /var/log/mysqld.log
其中有一段如下：
071112 0:22:06 [ERROR] /usr/local/mysql/bin/mysqld: Can't create/write to file '/var/run/mysqld/mysqld.pid' (Errcode: 2)
071112 0:22:06 [ERROR] Can't start server: can't create PID file: No such file or directory
071112 00:22:06 mysqld ended
#cd /var/run/
#ls
mysqld目录不存在，创建它： -------------------------------------------这是重点
#mkdir /var/run/mysqld
#cd /var/run/mysqld
创建文件mysqld.pid：
#touch mysqld.pid
#cd..
#chown -R mysql mysqld .
#cd /usr/local/mysql/
#bin/mysqld_safe --user=mysql &
nohup: ignoring input and redirecting stderr to stdout
Starting mysqld daemon with databases from /var/lib/mysql
能正常启动
#bin/mysqladmin -u root password root
又出错
[root@localhost mysql]# bin/mysqladmin -u root password root
bin/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!
[root@localhost mysql]# bin/mysql -u root -p
Enter password:
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)
分析：是/tmp/mysql.sock 不存在
# cd /var/lib/mysql/
由于mysql 默认的mysql.sock 是在/var/lib/mysql/mysql.sock，创建符号连接：
# ln -s /var/lib/mysql/mysql.sock /tmp/mysql.sock -----------------------------这是重点
# bin/mysql -u root
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 1
Server version: 5.0.45 MySQL Community Server (GPL)
Type 'help;' or 'h' for help. Type 'c' to clear the buffer.
mysql>
