MySQL安装故障排查：root用户本地登录权限问题求助

Step 1: Fix the Missing Socket Directory Error #

The Directory '/var/run/mysqld' don't exists error occurs because the required socket directory is missing or has incorrect permissions. Resolve this first:

• Stop the running MySQL service:

  sudo systemctl stop mysql
  

• Create the missing directory:

  sudo mkdir -p /var/run/mysqld
  

• Set correct ownership for the directory (must be owned by the mysql user):

  sudo chown mysql:mysql /var/run/mysqld
  

Step 2: Bypass Grant Tables to Reset Root Credentials #

Now you can start MySQL in safe mode and fix the access denied issue:

• Start MySQL with grant tables skipped:

  sudo mysqld_safe --skip-grant-tables &
  

• Log into MySQL without a password:

  mysql -u root
  

• Switch to the system database:

  USE mysql;
  

• Critical for MySQL 8.0: The old PASSWORD() function is deprecated. Reset the root user with mysql_native_password (compatible with standard password login):

  ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'your-new-strong-password';
  FLUSH PRIVILEGES;
  

• Exit MySQL:

  EXIT;
  

• Kill the safe mode process and restart the regular MySQL service:

  sudo pkill mysqld
  sudo systemctl start mysql
  

Step 3: Verify Login & Complete Setup #

• Log in with your new password:

  sudo mysql -u root -p
  

  Enter the password you set earlier, and you should gain access to the MySQL command line.
• Now you can run mysql_secure_installation to finish the security setup without errors.

Why Did the Original No-Password Login Fail? #

On Ubuntu 22.04, MySQL 8.0 defaults to using the auth_socket plugin for the root user instead of password authentication. This plugin only allows system-level root users (via sudo) to connect without a password—but if the plugin was modified during installation or a previous reset, this behavior breaks, leading to the Access denied error even with sudo mysql.

内容的提问来源于stack exchange，提问作者Mandar Gite