运行：systemctl start mysqld
错误：Job for mysqld.service failed because the control process exited with error code. See "systemctl status mysqld.service" and "journalctl -xe" for details.
mysqld.log中的提示：
2017-04-19T15:20:26.718566Z 0 [ERROR] InnoDB: Operating system error number 13 in a file operation.
2017-04-19T15:20:26.718643Z 0 [ERROR] InnoDB: The error means mysqld does not have the access rights to the directory.
2017-04-19T15:20:26.718655Z 0 [ERROR] InnoDB: os_file_get_status() failed on './ibdata1'. Can't determine file permissions
2017-04-19T15:20:26.718728Z 0 [ERROR] InnoDB: Plugin initialization aborted with error Generic error
2017-04-19T15:20:28.189585Z 0 [ERROR] Plugin 'InnoDB' init function returned error.
2017-04-19T15:20:28.189678Z 0 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2017-04-19T15:20:28.189696Z 0 [ERROR] Failed to initialize plugins.
2017-04-19T15:20:28.189708Z 0 [ERROR] Aborting
2017-04-19T15:20:28.189763Z 0 [Note] Binlog end
2017-04-19T15:20:28.192297Z 0 [Note] Shutting down plugin 'CSV'
2017-04-19T15:20:28.194679Z 0 [Note] /usr/sbin/mysqld: Shutdown complete
2017-04-19T15:20:31.320424Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2017-04-19T15:20:31.323827Z 0 [Warning] Insecure configuration for --secure-file-priv: Location is accessible to all OS users. Consider choosing a different directory.
2017-04-19T15:20:31.323949Z 0 [Note] /usr/sbin/mysqld (mysqld 5.7.18) starting as process 69981 ...
