Why can't Linux start mysql? How to deal with it?

When using Linux systems, MySQL is often used as a relational database management system. However, it is a common problem that MySQL fails to start under certain circumstances. This article will describe some of the causes of MySQL startup failure and provide some possible solutions to the problem.

First of all, there may be a problem with the MySQL configuration file, causing the startup to fail. Experienced administrators should know how to modify this file. The configuration file can be found with the following command:

sudo find / -name my.cnf

After finding the configuration file, the administrator needs to check the file for any syntax errors. To do this, enter the following command on the terminal:

sudo mysqlcheck -c /etc/my.cnf

If the administrator does not find the syntax error and MySQL still fails to start, the next possible problem may be related to permissions. Administrators can check the MySQL user's permissions by entering the following command in the terminal:

sudo mysql -u root -p -e 'SHOW GRANTS FOR root@localhost;'

Ensure that the MySQL user has the appropriate permissions to access the required files and directories. Administrators can try changing the MySQL user's password on the terminal to ensure that the user has the necessary permissions to access:

sudo mysql -u root -p -e "SET PASSWORD FOR 'root'@'localhost' = PASSWORD('new_password');"

However, if permissions are not an issue, it is more likely that some process for MySQL is still running. The administrator can find the running MySQL processes using the following command on the terminal:

ps -ef | grep mysql

Then the administrator needs to kill all the running MySQL processes using the following command:

sudo killall mysqld

The administrator can Try restarting MySQL using the following command:

sudo service mysqld start

If MySQL still cannot start at this time, try starting MySQL in single-user mode:

sudo mysqld --user=mysql --skip-grant-tables --skip-networking &

Administrators can view the MySQL logs in single-user mode To detect the error:

sudo tail -f /var/log/mysql/error.log

If none of the above methods solve the problem, you can try to reinstall MySQL. Administrators should back up their databases before reinstalling MySQL. Administrators can back up their database using the following command:

mysqldump -u root -p --all-databases > backup.sql

Reinstall MySQL:

sudo apt-get remove mysql-server
sudo apt-get autoremove
sudo apt-get install mysql-server

After the above steps, the administrator should be able to restart MySQL and access their database.

In short, MySQL startup failure may be caused by MySQL configuration files, permissions, running processes, or other unknown issues. Administrators should try to troubleshoot the above issues one by one and take appropriate action.

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