我下载的是目前最新的版本mysql-5.0.45-linux-i686.tar.gz
　　安装过程：
    su 到root 权限。
　　#tar -zvxf mysql-5.0.45-linux-i686.tar.gz
　　#mv mysql-5.0.45/ /usr/local/mysql
　　#cd /usr/local/mysql
　　#groupadd mysql
　　#useradd -g mysql mysql
　　#chown -R mysql .
　　#chgrp -R mysql .
　　#scripts/mysql_install_db --user=mysql
　　#chown -R root .
　　#chown -R mysql data
　　#bin/mysqld_safe --user=mysql &
　　按照官方文档说这就应该能启动了，可是报错如下：
　　
  
nohup: ignoring input and redirecting stderr to stdout
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
#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/
ibdata1      ib_logfile0  ib_logfile1  mysql/       mysql.sock   test/
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
# 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>

修改root 密码
#cd /usr/local/mysql/
#bin/mysqladmin -u root -p password yourpassword

一切ok.
一切ok...