Troubleshooting MySQL: Fixing '/var/lib/mysql/mysql.sock' Permission Denied Error for Non-MySQL Users on Linux Systems

If you've encountered the "/var/lib/mysql/mysql.sock" (13 "Permission Denied") error while attempting to access the MySQL socket as a non-MySQL user, it's likely due to inadequate permissions. This issue can prevent proper communication with the MySQL server. In this blog post, we'll explore the causes of this error and provide a step-by-step solution.

Understanding the Issue

The MySQL socket file, typically located at "/var/lib/mysql/mysql.sock," facilitates communication between client applications and the MySQL server. When a non-MySQL user encounters a "Permission Denied" error while trying to access this socket, it indicates that the user lacks the necessary permissions to interact with MySQL.

Diagnosing the Problem

Before proceeding with the solution, it's crucial to diagnose the issue. Here are some initial steps:

1. Check MySQL Service Status: Ensure that the MySQL service is running. Use the following command to verify its status:

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   sudo systemctl status mysql

2. Verify Socket Location: Confirm the location of the MySQL socket. The standard path is "/var/lib/mysql/mysql.sock." You can check the MySQL configuration file for the socket location:

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   grep -i socket /etc/mysql/my.cnf

Solution: Adjusting Permissions

To resolve the "Permission Denied" error, you'll need to adjust the permissions on the MySQL socket file. Follow these steps:

Step 1: Identify the MySQL User and Group

Determine the user and group associated with the MySQL server. This information is typically available in the MySQL configuration file. Commonly, the user is "mysql" and the group is also "mysql."

Step 2: Adjust Permissions

Set the correct ownership and permissions for the MySQL socket:

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sudo chown mysql:mysql /var/lib/mysql/mysql.sock sudo chmod 660 /var/lib/mysql/mysql.sock

These commands change the ownership to the MySQL user and group and grant read and write permissions.

Step 3: Restart MySQL Service

Restart the MySQL service to apply the changes:

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sudo systemctl restart mysql

Step 4: Verify Changes

Check the MySQL service status again to ensure it's running without issues:

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sudo systemctl status mysql

Now, attempt to access the MySQL socket as a non-MySQL user. The "Permission Denied" error should be resolved.

Conclusion

By adjusting the ownership and permissions of the MySQL socket file, you've successfully addressed the "/var/lib/mysql/mysql.sock" (13 "Permission Denied") error. This ensures proper communication between non-MySQL users and the MySQL server, facilitating a smoother experience for applications relying on MySQL services.