搭建Hadoop伪分布式环境

安装ssh client

yum install openssh-clients openssh-server
ssh localhost    //测试是否可以正常登陆

安装java环境

先安装jdk

yum install java-1.8.0-openjdk java-1.8.0-openjdk-devel
输入java和javac   //如果输出对应命令帮助，则表明jdk正确安装

配置java环境

vim ~/.bashrc    //添加
export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk
source ~/.bashrc    //生效环境变量
java -version   //检测java环境是否生效
$JAVA_HOME/bin/java -version  //若两条命令输出的结果一致，且都为我们前面安装的 openjdk-1.8.0 的版本，则表明 JDK 环境已经正确安装并配置

安装Hadoop

wget https://mirrors.tuna.tsinghua.edu.cn/apache/hadoop/common/hadoop-2.7.6/hadoop-2.7.6.tar.gz
tar -zxvf hadoop-2.7.6.tar.gz -C /usr/local/hadoop
/usr/local/hadoop/bin/hadoop version　　　//检查hadoop是否安装成功

Hadoop伪分布式环境配置

设置Hadoop的环境变量

vim ~/.bashrc　　　//添加
source ~/.bashrc　　//生效环境变量

修改Hadoop的配置文件

vim /usr/local/hadoop/etc/hadoop/core-site.xml　　//修改
<configuration>
    <property>
        <name>hadoop.tmp.dir</name>
        <value>file:/usr/local/hadoop/tmp</value>
        <description>location to store temporary files</description>
    </property>
    <property>
        <name>fs.defaultFS</name>
        <value>hdfs://localhost:9000</value>
    </property>
</configuration>


vim /usr/local/hadoop-2.7.6/etc/hadoop/hdfs-site.xml　　//修改
<configuration>
    <property>
        <name>dfs.replication</name>
        <value>1</value>
    </property>
    <property>
        <name>dfs.namenode.name.dir</name>
        <value>file:/usr/local/hadoop/tmp/dfs/name</value>
    </property>
    <property>
        <name>dfs.datanode.data.dir</name>
        <value>file:/usr/local/hadoop/tmp/dfs/data</value>
    </property>
</configuration>

格式化namenode

/usr/local/hadoop-2.7.6/bin/hdfs namenodes -format　

启动namenode和namenode守护进程

/usr/local/hadoop/sbin/start-dfs.sh 
Jps　//检查namenode和datanode是否安装成功

运行Hadoop伪分布式实例

cd /usr/local/hadoop/
../bin/hdfs dfs -mkdir -p /user/hadoop/input
./bin/hdfs dfs -put ./etc/hadoop/*.xml /user/hadoop/input

/usr/local/hadoop/bin/hdfs dfs -ls /user/hadoop/input  //查看上传的HDFS文件