错误描述：
[root@nna hadoop-3.2.2]# start-dfs.sh Starting namenodes on [nna nns] ERROR: Attempting to operate on hdfs namenode as root ERROR: but there is no HDFS_NAMENODE_USER defined. Aborting operation. Starting datanodes ERROR: Attempting to operate on hdfs datanode as root ERROR: but there is no HDFS_DATANODE_USER defined. Aborting operation. Starting journal nodes [dn1 dn3 dn2] ERROR: Attempting to operate on hdfs journalnode as root ERROR: but there is no HDFS_JOURNALNODE_USER defined. Aborting operation. Starting ZK Failover Controllers on NN hosts [nna nns] ERROR: Attempting to operate on hdfs zkfc as root ERROR: but there is no HDFS_ZKFC_USER defined. Aborting operation. [root@nna hadoop-3.2.2]# jps 2457 NameNode 2778 Jps [root@nna hadoop-3.2.2]#
解决方法：
在Hadoop安装目录下找到sbin文件夹
在里面修改四个文件
1、对于start-dfs.sh和stop-dfs.sh文件，添加下列参数：
HDFS_DATANODE_USER=root HADOOP_SECURE_DN_USER=hdfs HDFS_NAMENODE_USER=root
2、对于start-yarn.sh和stop-yarn.sh文件，添加下列参数：
YARN_RESOURCEMANAGER_USER=root HADOOP_SECURE_DN_USER=yarn YARN_NODEMANAGER_USER=root