cat: Call From jac/192.168.175.122 to localhost:9000 failed on connection exception: java.net.ConnectException: Connection refused; For more details see: http://wiki.apache.org/hadoop/ConnectionRefused
ANSWER:
bin/hdfs dfs -rm -r /user/hadoop/output
./bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-3.2.2.jar grep input output 'dfs[a-z.]+'