ERROR! MySQL is not running, but lock file (/var/lock/subsys/mysql) exists
1、MySQL数据库启动报错
Introduction
MySQL is a popular open-source relational database management system that is widely used for web development and other applications. However, sometimes you may encounter an error message like “ERROR! MySQL is not running, but lock file (/var/lock/subsys/mysql) exists”. This article will explain the possible causes for this error and provide solutions to resolve it.
介绍
MySQL是一个很受欢迎的关系型数据库管理系统，它普遍应用于web开发和其他应用中，然而有时候你会遇到报错，这篇文章将会解释报错产生的原因并提供解决方案。
Understanding the Error Message
The error message “ERROR! MySQL is not running, but lock file (/var/lock/subsys/mysql) exists” indicates that the MySQL service is not running even though there is a lock file present. In Linux systems, the lock file is used to prevent multiple instances of a service from running simultaneously.
了解错误信息
错误信息“ERROR! MySQL is not running, but lock file (/var/lock/subsys/mysql) exists”，表明MySQL服务没有运行，是因为有一个锁文件的存在，在Linux系统中，锁文件用于阻止一个应用的多个实例同时运行。
Possible Causes
There can be several reasons for this error to occur:
Improper shutdown:
1、 If the MySQL service was not properly shut down, it might leave behind the lock file without stopping the service.
2、System crash: A system crash or unexpected power outage can lead to the lock file remaining in place while the MySQL service is not running.
3、Incorrect file permissions: If the lock file has incorrect permissions, the MySQL service may not be able to start properly.
可能发生的原因
这个错误发生的几个原因：
1、MySQL服务没有正常关闭，它会产生锁文件来组织服务的启动；
2、系统崩溃：系统崩溃或者意外掉电，会保留锁定文件导致服务无法启动；
3、文件权限不正确，如果锁文件的权限不正确，会导致服务启动失败；
Resolving the Issue
To resolve the “MySQL is not running, but lock file exists” error, you can follow these steps:
Step 1: Remove the Lock File
The first step is to remove the lock file manually. Open your terminal and run the following command:
sudo rm /var/lock/subsys/mysql
This command will delete the lock file and allow the MySQL service to start fresh.
解决方案：
可以依据如下步骤解决MySQL不能启动的问题：
第一步：删除锁文件
第一步手动删除锁文件，连接中断执行如下命令；
这个命令会删除锁文件，让MySLQ梳理启动。
Step 2: Start the MySQL Service
After removing the lock file, you can attempt to start the MySQL service. Use the following command to start the service:
sudo service mysql start
If the service starts successfully, the error should be resolved.
第二步：启动MySQL服务
在删除锁文件后，你可以尝试启动MySQL服务，使用下面的命令启动服务
如果服务启动成功，那么这个报错就解决了；
Step 3: Verify MySQL Service Status
To confirm that the MySQL service is running, you can check its status using the following command:
sudo service mysql status
If the service is running, you should see a message indicating that the service is active.
第三步：验证MySQL服务
可以用如下命令来确认MySQL服务是否运行；
如果服务运行正常，你可以看到服务是active的提示；
Step 4: Restart the Server (if necessary)
In some cases, simply restarting the server can resolve the issue. You can restart the server using the following command:
sudo reboot
This step is optional and should only be performed if the previous steps did not resolve the error.
第四步：
在某些情况下，简单的重启服务也可以解决问题，你可以用以下命令重启服务；
这一步是可选的并且要确定上一步的操作没有解决这个问题。
Conclusion
The “MySQL is not running, but lock file exists” error can occur due to various reasons, such as improper shutdown, system crash, or incorrect file permissions. By removing the lock file, starting the MySQL service, and verifying its status, you can resolve this error and get your MySQL database up and running again. It is important to ensure that the MySQL service is properly shut down to avoid such errors in the future.
结论
“MySQL is not running, but lock file exists”导致这个报错的原因有很多，比如非正常关机，系统崩溃，文件权限异常。通过移除这个锁文件，启动MySQL服务，来确定他的状态，你可以解决这个报错让MySLQ数据库重新启动。你可以正确的关闭数据库来避免这个错误。
参考：https://blog.51cto.com/u_16175447/6660410
