Today, I modified the character set for the mysql database under Linux. In order to facilitate operation, I modified the permissions for the configuration file sudo Chmod 777 My.cnF

after modification, start: Job failed to start appears.
Nothing is printed in the
error log.

after the character set configuration is removed still prompt cannot start.

finally consider the possibility that only permissions have been modified due to permissions.

sudo chomd o-w my.cnf

sudo chmod g-w my.cnf

and then start MySQL.