/opt/hadoop-2.9.2/etc/hadoop/hadoop-env.sh

export JAVA_HOME=/usr/java/jdk1.8.0_161
export HADOOP_CONF_DIR=/opt/hadoop-2.9.2/etc/hadoop

/etc/profile

export JAVA_HOME=/usr/java/jdk1.8.0_161/
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:{JAVA_HOME}/lib:${JRE_HOME}/lib
export PATH=${JAVA_HOME}/bin:$PATH


export HADOOP_HOME=/opt/hadoop-2.9.2/
export HADOOP_CONF_DIR = /opt/hadoop-2.9.2/etc/hadoop
export PATH=$PATH:$HADOOP_HOME/bin:$HADOOP_HOME/sbin

/opt/hadoop-2.9.2/etc/hadoop/core-site.xml

<configuration>
<!--指定namenode服务器地址和通信端口号--> 
	<property> 
		<name>fs.defaultFS</name> 
		<value>hdfs://localhost:9000</value> 
	</property>
<!--指定namenode存放元数据的目录-->
	<property>
		<name>hadoop.tmp.dir</name>
		<value>/opt/hadoop-2.9.2/tmp</value>
	</property> 
</configuration>

/opt/hadoop-2.9.2/etc/hadoop/hdfs-site.xml

<configuration>
    <property>
        <name>dfs.namenode.name.dir</name>
        <value>/opt/hadoop-2.9.2/dfs/name</value>
    </property>
    <property>
        <name>dfs.datanode.data.dir</name>
        <value>/opt/hadoop-2.9.2/dfs/data</value>
    </property>
<!--指定数据块副本个数-->
    <property>
        <name>dfs.replication</name>
        <value>2</value>
    </property>
<!--设置secondary namenode-->
    <property>
        <name>dfs.namenode.secondary.http-address</name>
        <value>node2:9868</value>
    </property>
</configuration>

/etc/hosts

node1 ip1
node2 ip2
node3 ip3

主要参考：

https://blog.csdn.net/weixin_41732718/article/details/104643892?fromshare=blogdetail&sharetype=blogdetail&sharerId=104643892&sharerefer=PC&sharesource=2302_80120453&sharefrom=from_link