成功搭建Hadoop集群后简单实验

　　1> 检查对HDFS的访问(在namenode上操作)

　　#./hadoop-0.20.2/bin/hadoop fs -ls

　　2> hadoop中的文件系统操作

　　#./hadoop-0.20.2/bin/hadoop fs -mkdir test

　　#./hadoop-0.20.2/bin/hadoop fs -ls test

　　#./hadoop-0.20.2/bin/hadoop fs -rmr test

　　3> 测试hadoop

　　a> 创建子目录

　　#./hadoop-0.20.2/bin/hadoop fs -mkdir input

　　b> 把本地文件移动到hdfs

　　#./hadoop-0.20.2/bin/hadoop fs -put /usr/share/doc/pam-1.1.1/rfc86.0.txt input

　　#./hadoop-0.20.2/bin/hadoop fs -put /usr/share/doc/pam-1.1.1/Linux-PAM_SAG.txt input

　　c> 查看文件是否存在

　　#./hadoop-0.20.2/bin/hadoop fs -ls input

　　d> 执行计算单词频率的MapReduce作业

　　#./hadoop-0.20.2/bin/hadoop jar /root/hadoop-0.20.2/hadoop-0.20.2-examples.jar wordcount input output

　　Found 2 items

　　drwxr-xr-x - root supergroup 0 2012-11-26 04:25 /user/root/output/_logs

　　-rw-r--r-- 2 root supergroup 8315 2012-11-26 04:25 /user/root/output/part-r-00000

　　e> 查看输出结果

　　#./hadoop-0.20.2/bin/hadoop fs -ls output

　　#./hadoop-0.20.2/bin/hadoop fs -cat output/part-r-00000 | head -n 13

　　f> 从HDFS提取输出

　　#./hadoop-0.20.2/bin/hadoop fs -get output/part-r-00000 output.txt