故障现象：
[root@oradb mysql-5.6.27]# /app/oracle/oradata2/mysql-5.6.27/bin/mysqld_safe --defaults-file=/app/oracle/oradata2/mysql-5.6.27/my.cnf --user=mysql &
[1] 2695
[root@oradb mysql-5.6.27]# Warning: World-writable config file '/app/oracle/oradata2/mysql-5.6.27/my.cnf' is ignored
Warning: World-writable config file '/app/oracle/oradata2/mysql-5.6.27/my.cnf' is ignored
161008 22:07:19 mysqld_safe Logging to '/app/oracle/oradata2/mysql-5.6.27/data/oradb.err'.
161008 22:07:19 mysqld_safe Starting mysqld daemon with databases from /app/oracle/oradata2/mysql-5.6.27/data

原因： my.cnf 文件权限为 777 MYSQLD不读取该配置文件

处理：把 my.cnf 权限改为 644， chmod  644 my.cnf