[hadoop@LexiaofeiN1 ~]$ hdfs dfs -ls /output/grep

[hadoop@LexiaofeiN1 ~]$ hdfs dfs -rm -R /output/grep

[hadoop@LexiaofeiN1 ~]$ hdfs dfs -ls /output/grep

[hadoop@LexiaofeiN1 ~]$ cd /opt/modules/hadoop2.6

[hadoop@LexiaofeiN1 hadoop2.6]$ ./bin/hadoop jar ./share/hadoop/mapreduce/hadoop-mapreduce-examples-*.jar grep /input/grep /output/grep 'dfs[a-z.]+'

[hadoop@LexiaofeiN1 hadoop2.6]$ hdfs dfs -ls /output/grep

Found 2 items

-rw-r--r-- 1 hadoop supergroup 0 2017-03-23 16:27 /output/grep/_SUCCESS

-rw-r--r-- 1 hadoop supergroup 11 2017-03-23 16:27 /output/grep/part-r-00000