linux RedHat下安装mysql

linux下安装mysql的步骤，记录一下

linux版本：Red Hat Enterprise Linux Server release 6.6 (Santiago)

mysql版本：mysql-community-server-5.7.9

1. 到官网下载rpm包
   http://dev.mysql.com/downloads/mysql/
2. 检查是否安装过
   rpm -qa|grep mysql
   有则先删除
   rpm -e 
3. 使用yum安装，会自动识别依赖
   yum install mysql-community-{server,client,common,libs-compat,libs}-*
4. 启动mysql
   service mysqld start
5. 查看初始密码
   grep 'temporary password' /var/log/mysqld.log
   [Note] A temporary password is generated for root@localhost: B-loGAsAk5&A
6. 修改密码：
   mysqladmin -u root -p password "newpassword"
   Enter password:
   输入原来密码即可
   5.6以后默认启动密码校验插件，密码不能太简单，可以关闭
   mysql> use mysql; 
   mysql> UNINSTALL PLUGIN validate_password;
7. 连上mysql mysql -u root -p
8. 如果找不到初始密码，可以先用如下方式启动mysql
   service mysqld stop
   mysqld_safe --user=mysql --skip-grant-tables --skip-networking &
   在另外一个终端连上mysql ，这时不需要密码 
   mysql -u root
   UPDATE user SET authentication_string=PASSWORD('newpassword') where USER='root';
   service mysqld restart