LNMP start MySQL Error the server quit without updating PID file

Error code at startup:
Starting MySQL
[FAIL.] The server quit without updating PID file (/var/run/mysqld/mysqld.pid). ... failed!

Lnmp the author of the Army elder brother gives the answer is:

There is no error message in this, press [FAIL.] The server quit without updating PID file (/var/run/mysqld/mysqld.pid

This look may be another installation of MySQL or other configuration files caused, you can check if there is more/etc/mysql/my.cnf and other Mysl,

You can find the command and look at it.

After I delete the/etc/mysql/my.cnf file, the service MySQL start is successful and I do not know what caused it for the time being.

LNMP start MySQL Error the server quit without updating PID file