1.Caused by: org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.hdfs.server.n
amenode.SafeModeException): Cannot delete /output/.aa5fadaa-873e-4b6e-aa7c-42302
c5f8452. Name node is in safe mode.

关闭hadoop的安全模式  $hadoop dfsadmin -safemode leave

2.如果碰到匿名权限的问题,user:  is not allowed to impersonate
请设置core-site.xml

        <property>
                <name>hadoop.proxyuser.os的用户名.hosts</name>
                <value>*</value>
        </property>
        <property>
                <name>hadoop.proxyuser.os的用户名.groups</name>
                <value>*</value>
        </property>