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一、mysql_install_db说明
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当MySQL的系统库（mysql系统库）发生故障或需要新加一个mysql实例时，需要初始化mysql数据库。
需要使用的命令：/usr/local/mysql/bin/mysql_install_db
#/usr/local/mysql/bin/mysql_install_db --help 可以查看帮助信息如下
Usage: /usr/local/mysql/bin/mysql_install_db [OPTIONS]
--basedir=path The path to the MySQL installation directory.
--cross-bootstrap For internal use. Used when building the MySQL system
tables on a different host than the target.
--datadir=path The path to the MySQL data directory.
--force Causes mysql_install_db to run even if DNS does not
work. In that case, grant table entries that normally
use hostnames will use IP addresses.
--ldata=path The path to the MySQL data directory.
--rpm For internal use. This option is used by RPM files
during the MySQL installation process.
--skip-name-resolve Use IP addresses rather than hostnames when creating
grant table entries. This option can be useful if
your DNS does not work.
--srcdir=path For internal use. The directory under which
mysql_install_db looks for support files such as the
error message file and the file for popoulating the
help tables.
--user=user_name The login username to use for running mysqld. Files
and directories created by mysqld will be owned by this
user. You must be root to use this option. By default
mysqld runs using your current login name and files and
directories that it creates will be owned by you.
All other options are passed to the mysqld program
除了支持以上的参数，还支持mysqld的参数。
二、举例：
本文以新加一个mysql实例为例。例如服务器上已经安装了3306端口的mysql服务，需要再启一个3308端口的mysql服务。
假设mysql安装在/usr/local/mysql路径下，找一个磁盘空间剩余比较大的盘，如/data1，把3308端口的mysql的数据保存在/data1下
#mkdir /data1/mysql_3308
#mkdir /data1/mysql_3308/data
#chown -R mysql:mysql /data1/mysql_3308
复制一个mysql配置文件my.cnf到/data1/mysql_3308目录下
#vi /data1/mysql_3308/my.cnf
修改配置文件，将端口和相关目录的都改为新的设置，如下：
[client]
character-set-server = utf8
port = 3308
socket = /tmp/mysql_3308.sock
[mysqld]
user = mysql
port = 3308
socket = /tmp/mysql_3308.sock
basedir = /usr/local/mysql
datadir = /data1/mysql_3308/data
log-error = /data1/mysql_3308/mysql_error.log
pid-file = /data1/mysql_3308/mysql.pid
......其他略
确保配置文件无误。
运行下面命令进行数据库的初始化：
#/usr/local/mysql/bin/mysql_install_db --defaults-file=/data1/mysql_3308/my.cnf --datadir=/data1/mysql_3308/data
完成后新的3308数据库就初始化好了，如果有报错，则按照报错的提示查看报错日志，一般情况下都是my.cnf配置文件的问题，修正后即可。
三、启动新mysql
启动3308端口的mysql服务
#/usr/local/mysql/bin/mysqld_safe --defaults-file=/data1/mysql_3309/my.cnf
检查是否启动
#ps aux|grep mysql
如果有3308字样说明已经启动成功
可将启动命令加入/etc/rc.local随服务器启动
新加的mysql没有设置root密码，可以通过下面命令设置root密码：
#/usr/local/mysql/bin/mysqladmin -S /tmp/mysql_3308.sock -u root password 'new-password'
Mysql的配置文件:
!includedir /etc/mysql/conf.d/
!includedir /etc/mysql/mysql.conf.d/
这两行的意思是配置文件在这两个目录下，也就是说你可以在这两个目录下配置，最好是不要直接改变
my.cnf文件, 因为它会导致一些问题, 比如当在升级 Ubuntu/Mysql 到一个新的版本时.这里我们创建一个新文件：sudo vim
/etc/mysql/conf.d/utf8.cnf
utf8.cnf配置文件内容为：
[mysqld]
character-set-server=utf8
collation-server=utf8_general_ci
[client]
default-character-set=utf8
有三种方法:
方法一(不推荐)、本地登入mysql，更改 "mysql" 数据库里的 "user" 表里的 "host" 项，将"localhost"改为"%"
#mysql -u root -proot
mysqluse mysql;
mysqlupdate user set host = '%' where user = 'root';
mysqlselect host, user from user;
方法二、直接授权(推荐)
从任何主机上使用root用户，密码：youpassword（你的root密码）连接到mysql服务器：（首先登陆Linux服务器，填写下面代码即可）
[root@localhost software]# mysql -u root -proot
mysqlGRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'youpassword' WITH GRANT OPTION;
mysqlFLUSH PRIVILEGES;
操作完后切记执行以下命令刷新权限
FLUSH PRIVILEGES;
方法三：终极方法
注释bind-address = 127.0.0.1
找到mysql.cnf
把bind-address = 127.0.0.1 前面加上 #
即 #bind-address = 127.0.0.1
