1. 配置集群
2. 齐心协力集群
3. 执行案例
   1.配置hadoop-env.sh文件

把上面的路径写到文件中，vi或者NotePad++文件都可以。

在/etc/hadoop/hadoop-env.sh中添加

export JAVA_HOME=/opt/module/jdk1.8.0_144

配置core-site.xml

<property>
<name>fs.defaultFS</name>
    <value>hdfs://hadoop101:9000</value>
</property>

<!-- 指定Hadoop运行时产生文件的存储目录 -->
<property>
    <name>hadoop.tmp.dir</name>
    <value>/opt/module/hadoop-2.7.2/data/tmp</value>
</property>

配置hdfs-site.xml

<property>
    <name>dfs.replication</name>
    <value>1</value>
</property>

2.启动集群

主节点Namenode(不可以总是格式化，集群的id会变化）

bin/hdfs namenode -format

启动NameNode

sbin/hadoop-demon.sh start namenode

齐心协力DataNode

sbin/hadoop-daemon.sh start datanode

查处集群

jps

小心：jps是JDK的命令，Hadoop是java写的，也需要安装JDK.

http://hadoop101:50070/dfshealth.html#tab-overview

伪分布式启动hdfs(Hadoop Dir file System)
创建文件input


查看上传的文件是否正确

bin/hdfs dfs -ls  /user/dev1/input/
bin/hdfs dfs -cat  /user/dev1/input/word.txt

运行MapReduce

bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.2.jar wordcount /user/dev1/input/ /user/dev1/output

查看成功的结果：
bin/hdfs dfs -cat /user/dev1/output/*

配置yarn-site.xml

在dev1下面操作

sudo vim yarn-site.xml

文件中加上：

<property>
<name>yarn.log-aggregation-enable</name>
<value>true</value>
</property>

<!-- 日志保留时间设置7天 -->
<property>
<name>yarn.log-aggregation.retain-seconds</name>
<value>604800</value>
</property>

启动NodeManager,ResourceManager和HistoryManager

sbin/yarn-daemon.sh start resourcemanager
sbin/yarn-daemon.sh start nodemanager
sbin/mr-jobhistory-daemon.sh start historyserver

jps
6150 NodeManager
5912 ResourceManager
6284 JobHistoryServer
6317 Jps

执行WordCount

bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.2.jar wordcount /user/dev1/input /user/dev1/output

全部的代码附上
history

    1  java -version
    2  ls
    3  cd etc
    4  ls
    5  cd hadoop/
    6  ls
    7  vi yarn-site.xml 
    8  sbin/yarn-daemon.sh start resourcemanager
    9  sbin/yarn-daemon.sh start nodemanager
   10  sbin/mr-jobhistory-daemon.sh start historyserver
   11  sbin/yarn-daemon.sh start resourcemanager
   12  cd ..
   13  ls
   14  sbin/yarn-daemon.sh start resourcemanager
   15  sbin/yarn-daemon.sh start nodemanager
   16  sbin/mr-jobhistory-daemon.sh start historyserver
   17  jps
   18  bin/hdfs dfs -rm -R /user/dev1/output
   19  bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-example

s-2.7.2.jar wordcount /user/dev1/input /user/dev1/output