hadoop机群 运行wordcount出现 Input path does not exist: hdfs://ns1/user/root/a.txt

机群搭建好，执行自带wordcount时出现： Input path does not exist: hdfs://ns1/user/root/a.txt 此错误。

[root@slave1 hadoop]# ls

a.txt  dfs1  include  libexec      name        sbin   test  tmp2

bin    etc   journal  LICENSE.txt  NOTICE.txt  share  tmp   zookeeper.out

data   hdfs  lib      logs         README.txt  src    tmp1

[root@slave1 hadoop]# bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.4.jar wordcount a.txt /mrout  

17/11/10 17:44:39 INFO mapreduce.JobSubmitter: Cleaning up the staging area /tmp/hadoop-yarn/staging/root/.staging/job_1510302622448_0003 

org.apache.hadoop.mapreduce.lib.input.InvalidInputException: Input path does not exist: hdfs://ns1/user/root/a.txt                                                                  

 出错原因：单机读取的是本地的文件，分布式环境下需要从hdfs 上读取文件。 

将本地的文件上传到hdfs上，然后再运行wordcount可以成功执行。

[root@slave1 hadoop]# bin/hdfs dfs -mkdir /input

[root@slave1 hadoop]# bin/hdfs dfs iput test/a.txt /input

[root@slave1 hadoop]# bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.4.jar wordcount /input/a.txt /mrout2

17/11/13 10:22:48 INFO input.FileInputFormat: Total input paths to process : 1

17/11/13 10:22:49 INFO mapreduce.JobSubmitter: number of splits:1

17/11/13 10:22:49 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1510302622448_0010

17/11/13 10:22:50 INFO impl.YarnClientImpl: Submitted application application_1510302622448_0010

17/11/13 10:22:50 INFO mapreduce.Job: The url to track the job: http://master:8088/proxy/application_1510302622448_0010/

17/11/13 10:22:50 INFO mapreduce.Job: Running job: job_1510302622448_0010