当前主机复制远程mysql库数据时报错：
#mysqldump -h远程主机 -uroot -p远程mysql密码 -P3306 --default-character-set=utf8 --all-databases | mysql -h127.0.0.1 -uroot -p -P3306
ERROR 1044 (42000): Access denied for user 'root'@'localhost'
解决办法： 给localhost开放权限
#mysql -uroot -p
输入密码
#查看各root账号的权限：
mysql> select current_user() from dual;
+----------------+
| current_user() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
mysql> select host,user from user where user='root';
ERROR 1046 (3D000): No database selected
mysql> use mysql;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> select host,user from user where user='root';
+-----------+------+
| host | user |
+-----------+------+
| localhost | root |
+-----------+------+
1 row in set (0.00 sec)
mysql> show grants for root@'localhost';
+---------------------------------------------------------------------+
| Grants for root@localhost |
+---------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION |
| GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION |
+---------------------------------------------------------------------+
2 rows in set (0.00 sec)
mysql> show grants for root@'127.0.0.1';
ERROR 1141 (42000): There is no such grant defined for user 'root' on host '127.0.0.1'
mysql> show grants for root@'%';
ERROR 1141 (42000): There is no such grant defined for user 'root' on host '%'
mysql> show grants for root@'xxx.xxx.xxx.xxx';
ERROR 1141 (42000): There is no such grant defined for user 'root' on host 'xxx.xxx.xxx.xxx'
如上所示，root@localhost账号没有访问权限及WITH GRANT OPTION选项，关于WITH GRANT OPTION选项，如果想让授权的用户，也可以将这些权限授予给其他用户，需要选项 “WITH GRANT OPTION“ 。也就是说有这个选项就可以将权限传递给第三方。这也是上面root@localhost用户给其它用后授权报错的原因，如果以 root@127.0.0.1登录（此账号拥有WITHGRANT OPTION选项），创建用户并授权就不会有这个错误，如下所示：
#给IP-xxx.xxx.xxx.xxx赋予远程访问权限：
# mysql -h127.0.0.1 -u root
(需先设置密码：
mysql> set global validate_password_length=6;
Query OK, 0 rows affected (0.00 sec)
mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.00 sec)
mysql> set password for root@localhost = password('123456');
Query OK, 0 rows affected, 1 warning (0.00 sec) )
设置密码的直接输入:
# mysql -h127.0.0.1 -u root -p
>grant all privileges on *.* to root@"127.0.0.1" identified by "密码" WITH GRANT OPTION;
#生效设置：
>FLUSH PRIVILEGES;