Hadoop3 启动服务，提示：Attempting to operate on hdfs namenode as root

在刚刚安装Hadoop3 环境上，启动Hadoop3,给出如下提示信息：Attempting to operate on hdfs namenode as root

翻译：尝试使用root 账户去操作hdfs namenode

造成原因：缺少用户定义

解决办法：

在/hadoop/sbin路径下： 
将start-dfs.sh，stop-dfs.sh两个文件顶部添加以下参数

#!/usr/bin/env bash 
HDFS_DATANODE_USER=root 
HADOOP_SECURE_DN_USER=hdfs 
HDFS_NAMENODE_USER=root 
HDFS_SECONDARYNAMENODE_USER=root 

还有，start-yarn.sh，stop-yarn.sh顶部也需添加以下：

#!/usr/bin/env bash 
YARN_RESOURCEMANAGER_USER=root 
HADOOP_SECURE_DN_USER=yarn 
YARN_NODEMANAGER_USER=root 
 
 
# Licensed to the Apache Software Foundation (ASF) under one or more 

修改后重启 ./start-dfs.sh，成功！

[root@master sbin]# ./start-dfs.sh 
WARNING: HADOOP_SECURE_DN_USER has been replaced by HDFS_DATANODE_SECURE_USER. Using value of HADOOP_SECURE_DN_USER. 
Starting namenodes on [master] 
上一次登录：日 6月  3 03:01:37 CST 2018从 slave1pts/2 上 
master: Warning: Permanently added 'master,192.168.43.161' (ECDSA) to the list of known hosts. 
Starting datanodes 
上一次登录：日 6月  3 04:09:05 CST 2018pts/1 上 
Starting secondary namenodes [slave1] 
上一次登录：日 6月  3 04:09:08 CST 2018pts/1 上