Starting MySQL. ERROR! The server quit without updating PID file (/usr/local/jianglin/mysql-5.7.26/data/localhost.localdomain.pid).

The error message you received indicates that MySQL server was unable to start properly due to an issue with updating the PID (Process ID) file. This file is used to track the running process of the MySQL server.

To troubleshoot this issue, you can try the following steps:

1. Check the file permissions: Ensure that the user running the MySQL server has proper permissions to read and write to the PID file directory. You can use the `ls -l` command to check the permissions.

2. Verify the directory path: Make sure that the directory path mentioned in the error message (`/usr/local/jianglin/mysql-5.7.26/data/`) exists and is correct. If not, you may need to update the MySQL configuration file (`my.cnf`) with the correct path.

3. Remove the PID file: If the PID file exists, remove it manually and then try starting MySQL again. You can use the following command to remove the PID file:

   sudo rm /usr/local/jianglin/mysql-5.7.26/data/localhost.localdomain.pid

4. Check for any other running instances: Ensure that there are no other instances of MySQL already running on the system. You can use the `ps -ef | grep mysql` command to check if there are any MySQL processes running, and kill them if necessary.

5. Review MySQL error logs: Check the MySQL error logs (usually located in `/var/log/mysql/` or specified in `my.cnf`) for any additional information about the error. The logs can provide more insights into the cause of the issue.

If none of the above steps resolve the problem, please provide more details about your MySQL setup, any recent changes made, and any relevant log entries for further assistance.