我是学习Hadoop的新手。而且我在配置方面遇到了一些问题。在此之前，我完成了JAVA，SSH，core-site.xml，hdfs-site.xml和hadoop-env.sh的配置。请告诉我该如何解决。非常感谢。
root@host1-virtual-machine:/home/host1/usr/hadoop-3.2.1# sbin/start-all.sh
Starting namenodes on [localhost]
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 secondary namenodes [host1-virtual-machine]
ERROR: Attempting to operate on hdfs secondarynamenode as root
ERROR: but there is no HDFS_SECONDARYNAMENODE_USER defined. Aborting operation.
2020-02-12 13:19:37,322 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Starting resourcemanager
ERROR: Attempting to operate on yarn resourcemanager as root
ERROR: but there is no YARN_RESOURCEMANAGER_USER defined. Aborting operation.
Starting nodemanagers
ERROR: Attempting to operate on yarn nodemanager as root
ERROR: but there is no YARN_NODEMANAGER_USER defined. Aborting operation.
我在hadoop-env.sh中添加5行后，它发出以下警告：
Starting namenodes on [localhost]
localhost: root@localhost: Permission denied (publickey,password).
Starting datanodes
localhost: root@localhost: Permission denied (publickey,password).
Starting secondary namenodes [host1-virtual-machine]
host1-virtual-machine: root@host1-virtual-machine: Permission denied (publickey,password).
2020-02-12 20:26:27,702 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Starting resourcemanager
Starting nodemanagers
localhost: root@localhost: Permission denied (publickey,password).
此问题的原因是在安装和启动服务时使用了不同的用户。您可以在hadoop-env.sh中将用户定义为root用户，如下所示：
export HDFS_NAMENODE_USER=root
export HDFS_DATANODE_USER=root
export HDFS_SECONDARYNAMENODE_USER=root
export YARN_RESOURCEMANAGER_USER=root
export YARN_NODEMANAGER_USER=root
希望这会有所帮助