在服务器初始启动时，假设服务器的数据目录为空，会发生以下情况:

完成服务器的初始化。 在data目录下生成SSL证书和密钥文件。 安装并启用validate_password插件。 创建超级用户帐户“root”@“localhost”。超级用户的密码被设置并存储在错误日志文件中。 要显示它，使用以下命令:

Shell > sudo grep '临时密码' /var/log/mysqld.log

请使用临时密码登录，并自定义超级用户密码，尽快修改root用户密码:

Shell > mysql的root -p

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPass5!

答案可能听起来很傻，但在浪费了几个小时的时间后，我是这样做到的:

mysql -u root -p

我收到了错误信息

错误1045(28000):拒绝访问用户'root'@'localhost'(使用密码:YES)

尽管我输入了正确的密码(你第一次安装MySQL时得到的临时密码)。

当密码提示闪烁时，我输入了密码。

如果问题仍然存在，请尝试强制修改密码:

/etc/init.d/mysql stop

mysqld_safe --skip-grant-tables &

mysql -u root

设置新的MySQL root用户密码:

use mysql;
update user set password=PASSWORD("NEW-ROOT-PASSWORD") where User='root';
flush privileges;
quit;

停止MySQL服务器:

/etc/init.d/mysql stop

启动MySQL服务器并测试它:

mysql -u root -p

如果其他答案都不适合您，并且您收到了以下错误:

mysqld_safe Logging to '/var/log/mysql/error.log'.
mysqld_safe Directory '/var/run/mysqld' for UNIX socket file don't exists.
[1]+  Exit 1                  sudo mysqld_safe --skip-grant-tables

按照以下命令依次执行，直到重置密码:

# Stop your server first
sudo service mysql stop

# Make the MySQL service directory.
sudo mkdir /var/run/mysqld

# Give MySQL permission to work with the created directory
sudo chown mysql: /var/run/mysqld

# Start MySQL, without permission and network checking
sudo mysqld_safe --skip-grant-tables --skip-networking &

# Log in to your server without any password.
mysql -u root mysql


# Update the password for the root user:
UPDATE mysql.user SET authentication_string=PASSWORD('YourNewPasswordBuddy'), plugin='mysql_native_password' WHERE User='root' AND Host='localhost';

# If you omit (AND Host='localhost') section, it updates
# the root password regardless of its host

FLUSH PRIVILEGES;
EXIT;

# Kill the mysqld_safe process
sudo service mysql restart

# Now you can use your new password to log in to your server
mysql -u root -p

# Take note for remote access. You should create a remote
# user and then grant all privileges to that remote user

我可以通过执行这条语句来解决这个问题

sudo dpkg-reconfigure mysql-server-5.5

这将改变根密码。

我使用的是mysql-5.7.12-osx10.11-x86_64。dmg在Mac OS X上。

安装过程会自动为root用户设置一个临时密码。你应该保存密码。密码不可恢复。

按照说明操作:

Go to cd /usr/local/mysql/bin/ Enter the temporary password (which would look something like, "tsO07JF1=>3") You should get the mysql> prompt. Run, SET PASSWORD FOR 'root'@'localhost' = PASSWORD('{YOUR_PASSWORD}'); If you wish to set your password: "root" then the command would be, SET PASSWORD FOR 'root'@'localhost' = PASSWORD('root'); Run ALTER USER 'root'@'localhost' PASSWORD EXPIRE NEVER; Run exit Run ./mysql -u root -p Type your password. In my case I would type, "root" (without quote) That's all.

为了方便起见，您应该在PATH环境变量中添加“/usr/local/mysql/bin”。

现在你可以在任何地方输入。/mysql -u root -p，然后输入密码，你会得到mysql>提示。