--连接远程的数据库shell> mysql -h host -u user -p--连接本地数据库shell> mysql -u user -p

-bash-4.1$ mysql -uroot -pMyNewPass4!mysql: [Warning] Using a password on the command line interface can be insecure.Welcome to the MySQL monitor. Commands end with ; or \g.Your MySQL connection id is 18Server version: 8.0.23 MySQL Community Server - GPL
Copyright (c) 2000, 2021, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>

mysql> exitBye
或者mysql> quitBye
或者mysql> \qBye
或者 Control+Dmysql> ^DBye

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

-bash-4.1$ sudo service mysqld stopStopping mysqld: [ OK ]
--连接报错-bash-4.1$ mysql -uroot -pMyNewPass4!mysql: [Warning] Using a password on the command line interface can be insecure.ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
--启动mysql-bash-4.1$ sudo service mysqld startStarting mysqld: [ OK ]
--正常连接-bash-4.1$ mysql -uroot -pMyNewPass4!mysql: [Warning] Using a password on the command line interface can be insecure.Welcome to the MySQL monitor. Commands end with ; or \g.Your MySQL connection id is 9Server version: 8.0.23 MySQL Community Server - GPL
Copyright (c) 2000, 2021, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>

-bash-4.1$ mysql -h <hostname> -uroot -pMyNewPass4!mysql: [Warning] Using a password on the command line interface can be insecure.ERROR 1130 (HY000): Host '<hostname>' is not allowed to connect to this MySQL server

$ mysql -u root -pmysql> show databases;mysql> use mysql;mysql> select host,user from user;mysql> update user set host = '%' where user = 'root';mysql> flush privileges; 或者重启MySQL
--成功登录$ mysql -h <hostname> -uroot -p
例：-bash-4.1$ mysql -u root -p -pmysql> show databases;+--------------------+| Database |+--------------------+| information_schema || mysql || performance_schema || sys |+--------------------+4 rows in set (0.01 sec)
mysql> use mysql;Reading table information for completion of table and column namesYou can turn off this feature to get a quicker startup with -A
Database changedmysql> select host,user from user;+-----------+------------------+| host | user |+-----------+------------------+| localhost | mysql.infoschema || localhost | mysql.session || localhost | mysql.sys || localhost | root |+-----------+------------------+4 rows in set (0.01 sec)

mysql> update user set host = '%' where user = 'root';Query OK, 1 row affected (0.04 sec)Rows matched: 1 Changed: 1 Warnings: 0
mysql> select host,user from user;+-----------+------------------+| host | user |+-----------+------------------+| % | root || localhost | mysql.infoschema || localhost | mysql.session || localhost | mysql.sys |+-----------+------------------+4 rows in set (0.01 sec)
mysql> flush privileges;Query OK, 0 rows affected (0.01 sec)
mysql> exitBye
--成功登录-bash-4.1$ mysql -h <hostname> -uroot -pEnter password:Welcome to the MySQL monitor. Commands end with ; or \g.Your MySQL connection id is 22Server version: 8.0.23 MySQL Community Server - GPL
Copyright (c) 2000, 2021, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>

-bash-4.1$ mysql -h <hostname> -uroot -pEnter password:ERROR 1251 (08004): Client does not support authentication protocol requested by server; consider upgrading MySQL client