根据我的经验，如果你没有sudo，它是行不通的。所以确保你的命令是;

sudo mysql -uroot -p

如果你像我一样，在前面的答案中所有的信息都失败了，继续卸载你机器上的所有版本的MySQL，使用命令sudo find / name " MySQL "和rm -rf每个附加" MySQL "名称的文件或目录(你应该跳过与编程语言库相关的文件)搜索所有剩余的MySQL文件。

现在安装一个新版本的MySQL，开始享受吧。注:你将失去所有的数据，所以先权衡你的选择。

之前的答案都没有帮助我解决这个问题，所以这里是我找到的解决方案。

相关部分:

In Ubuntu systems running MySQL 5.7 (and later versions), the root MySQL user is set to authenticate using the auth_socket plugin by default rather than with a password. This allows for some greater security and usability in many cases, but it can also complicate things when you need to allow an external program (e.g., phpMyAdmin) to access the user. In order to use a password to connect to MySQL as root, you will need to switch its authentication method from auth_socket to mysql_native_password. To do this, open up the MySQL prompt from your terminal: sudo mysql Next, check which authentication method each of your MySQL user accounts use with the following command: SELECT user,authentication_string,plugin,host FROM mysql.user; Output +------------------+-------------------------------------------+-----------------------+-----------+ | user | authentication_string | plugin | host | +------------------+-------------------------------------------+-----------------------+-----------+ | root | | auth_socket | localhost | | mysql.session | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost | | mysql.sys | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost | | debian-sys-maint | *CC744277A401A7D25BE1CA89AFF17BF607F876FF | mysql_native_password | localhost | +------------------+-------------------------------------------+-----------------------+-----------+ 4 rows in set (0.00 sec) In this example, you can see that the root user does in fact authenticate using the auth_socket plugin. To configure the root account to authenticate with a password, run the following ALTER USER command. Be sure to change password to a strong password of your choosing, and note that this command will change the root password you set in Step 2: ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password'; Then, run FLUSH PRIVILEGES which tells the server to reload the grant tables and put your new changes into effect: FLUSH PRIVILEGES; Check the authentication methods employed by each of your users again to confirm that root no longer authenticates using the auth_socket plugin: SELECT user,authentication_string,plugin,host FROM mysql.user; Output +------------------+-------------------------------------------+-----------------------+-----------+ | user | authentication_string | plugin | host | +------------------+-------------------------------------------+-----------------------+-----------+ | root | *3636DACC8616D997782ADD0839F92C1571D6D78F | mysql_native_password | localhost | | mysql.session | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost | | mysql.sys | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost | | debian-sys-maint | *CC744277A401A7D25BE1CA89AFF17BF607F876FF | mysql_native_password | localhost | +------------------+-------------------------------------------+-----------------------+-----------+ 4 rows in set (0.00 sec) You can see in this example output that the root MySQL user now authenticates using a password. Once you confirm this on your own server, you can exit the MySQL shell: exit

对于新Linux用户来说，这可能是一项艰巨的任务。让我用MySQL 8更新这个(目前可用的最新版本是8.0.12，截至2018-09-12)

Open "mysqld.cnf" configuration file at "/etc/mysql/mysql.conf.d/". Add skip-grant-tables to the next line of [mysql] text and save. Restart the MySQL service as "sudo service mysql restart". Now your MySQL is free of any authentication. Connect to the MySQL client (also known as mysql-shell) as mysql -u root -p. There is no password to be keyed in as of now. Run SQL command flush privileges; Reset the password now as ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPassword'; Now let's get back to the normal state; remove that line "skip-grant-tables" from "mysqld.cnf" and restart the service.

就是这样。

对于Ubuntu/Debian用户

(它可能适用于其他发行版，尤其是基于debian的发行版。)

运行以下命令以root身份连接(不需要任何密码)

sudo /usr/bin/mysql --defaults-file=/etc/mysql/debian.cnf

如果你不想每次以根用户连接时都添加——defaults-file，你可以将/etc/mysql/debian.cnf复制到你的主目录:

sudo cp /etc/mysql/debian.cnf ~/.my.cnf

然后:

sudo mysql

窗口:

cd \ampps\mysql\bin ：

mysql.exe -u root -pmysql

mysql启动后(可以看到shell是这样的mysql>) 使用这个查询:

 ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'root';

请再次使用root访问