Hadoop-实例WordCount

Hadoop必须要启动了才行哟，不要问我为什么会知道。

1.退出安全模式

/opt/hadoop/hadoop272/bin/hadoop dfsadmin -safemode leave

启动就是 enter

2.上传数据到hadoop

2.1新建存放的目录

/opt/hadoop/hadoop272/bin/hadoop fs -mkdir /input

2.2传数据到指定目录

/opt/hadoop/hadoop272/bin/hadoop fs -put /opt/hadoop/data/file1.txt /input

3.启动jar程序

/opt/hadoop/hadoop272/bin/hadoop jar /opt/hadoop/hadoop272/share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.2.jar wordcount /input /output

4.查看结果

4.1查看/output下的目录结构

/opt/hadoop/hadoop272/bin/hadoop fs -ls /output

4.2查看统计结果

/opt/hadoop/hadoop272/bin/hadoop fs cat /output/part-r-00000

5.重新上传

5.1删除 /input中的file1

/opt/hadoop/hadoop272/bin/hadoop fs -rm /input/file1.txt

5.2删除/output

/opt/hadoop/hadoop272/bin/hadoop fs -rm -r /output

5.3跳到2.2开始执行