测试wordcount
vi a.txt
hello you
hello me

cd /usr/local/hadoop-2.7.0/
./bin/hdfs dfs -put a.txt /
./bin/hdfs dfs -rm -r /out/   删除之前的结果 
./bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.0.jar wordcount /a.txt /out
./bin/hdfs dfs -text /out/part-r-00000  查看结果