I have installed hadoop-1.0.3 in my system(14.04), followed this tutorial.

And I successfully run an sample mapreduce program for wordcount as follows,

hadoopuser@arul-PC:/usr/local/hadoop$ bin/hadoop jar hadoop*examples*.jar wordcount /user/hadoopuser/SampleData /user/hadoopuser/SampleOutput
14/06/17 15:25:45 INFO input.FileInputFormat: Total input paths to process : 3
14/06/17 15:25:45 INFO util.NativeCodeLoader: Loaded the native-hadoop library
14/06/17 15:25:45 WARN snappy.LoadSnappy: Snappy native library not loaded
14/06/17 15:25:45 INFO mapred.JobClient: Running job: job_201406171444_0002
14/06/17 15:25:46 INFO mapred.JobClient:  map 0% reduce 0%
14/06/17 15:26:04 INFO mapred.JobClient:  map 66% reduce 0%
14/06/17 15:26:13 INFO mapred.JobClient:  map 100% reduce 0%
14/06/17 15:26:16 INFO mapred.JobClient:  map 100% reduce 22%
14/06/17 15:26:28 INFO mapred.JobClient:  map 100% reduce 100%
14/06/17 15:26:33 INFO mapred.JobClient: Job complete: job_201406171444_0002
14/06/17 15:26:33 INFO mapred.JobClient: Counters: 29
14/06/17 15:26:33 INFO mapred.JobClient:   Job Counters 
14/06/17 15:26:33 INFO mapred.JobClient:     Launched reduce tasks=1
14/06/17 15:26:33 INFO mapred.JobClient:     SLOTS_MILLIS_MAPS=33037
14/06/17 15:26:33 INFO mapred.JobClient:     Total time spent by all reduces waiting after reserving slots (ms)=0
14/06/17 15:26:33 INFO mapred.JobClient:     Total time spent by all maps waiting after reserving slots (ms)=0
14/06/17 15:26:33 INFO mapred.JobClient:     Launched map tasks=3
14/06/17 15:26:33 INFO mapred.JobClient:     Data-local map tasks=3
14/06/17 15:26:33 INFO mapred.JobClient:     SLOTS_MILLIS_REDUCES=21208
14/06/17 15:26:33 INFO mapred.JobClient:   File Output Format Counters 
14/06/17 15:26:33 INFO mapred.JobClient:     Bytes Written=880838
14/06/17 15:26:33 INFO mapred.JobClient:   FileSystemCounters
14/06/17 15:26:33 INFO mapred.JobClient:     FILE_BYTES_READ=2214875
14/06/17 15:26:33 INFO mapred.JobClient:     HDFS_BYTES_READ=3671899
14/06/17 15:26:33 INFO mapred.JobClient:     FILE_BYTES_WRITTEN=3775759
14/06/17 15:26:33 INFO mapred.JobClient:     HDFS_BYTES_WRITTEN=880838
14/06/17 15:26:33 INFO mapred.JobClient:   File Input Format Counters 
14/06/17 15:26:33 INFO mapred.JobClient:     Bytes Read=3671523
14/06/17 15:26:33 INFO mapred.JobClient:   Map-Reduce Framework
14/06/17 15:26:33 INFO mapred.JobClient:     Map output materialized bytes=1474367
14/06/17 15:26:33 INFO mapred.JobClient:     Map input records=77931
14/06/17 15:26:33 INFO mapred.JobClient:     Reduce shuffle bytes=1207341
14/06/17 15:26:33 INFO mapred.JobClient:     Spilled Records=255966
14/06/17 15:26:33 INFO mapred.JobClient:     Map output bytes=6076101
14/06/17 15:26:33 INFO mapred.JobClient:     Total committed heap usage (bytes)=517210112
14/06/17 15:26:33 INFO mapred.JobClient:     CPU time spent (ms)=11530
14/06/17 15:26:33 INFO mapred.JobClient:     Combine input records=629172
14/06/17 15:26:33 INFO mapred.JobClient:     SPLIT_RAW_BYTES=376
14/06/17 15:26:33 INFO mapred.JobClient:     Reduce input records=102324
14/06/17 15:26:33 INFO mapred.JobClient:     Reduce input groups=82335
14/06/17 15:26:33 INFO mapred.JobClient:     Combine output records=102324
14/06/17 15:26:33 INFO mapred.JobClient:     Physical memory (bytes) snapshot=589725696
14/06/17 15:26:33 INFO mapred.JobClient:     Reduce output records=82335
14/06/17 15:26:33 INFO mapred.JobClient:     Virtual memory (bytes) snapshot=1862012928
14/06/17 15:26:33 INFO mapred.JobClient:     Map output records=629172

When I check the output file it is present in output folder,

hadoopuser@arul-PC:/usr/local/hadoop$ bin/hadoop dfs -ls /user/hadoopuser/SampleOutput
Found 3 items
-rw-r--r--   1 hadoopuser supergroup          0 2014-06-17 15:26 /user/hadoopuser/SampleOutput/_SUCCESS
drwxr-xr-x   - hadoopuser supergroup          0 2014-06-17 15:25 /user/hadoopuser/SampleOutput/_logs

-rw-r--r-- 1 hadoopuser supergroup 880838 2014-06-17 15:26 /user/hadoopuser/SampleOutput/part-r-00000

I tried to open it using following command,

hadoopuser@avvenire-PC:/usr/local/hadoop$ bin/hadoop dfs -cat /user/hadoopuser/SampleOutput/part-r-0000

But I am getting result as follows,

cat: File does not exist: /user/hadoopuser/SampleOutput/part-r-0000

Please provide me a solution. Thank in advance.

up vote 1 down vote accepted

Check the file name. Its five 0's not four.

bin/hadoop dfs -cat /user/hadoopuser/SampleOutput/part-r-00000

So I realize that an answer has already been accepted, but here's the solution when it happened to me (just incase anyone else sees this thread).


TLDR; make sure there aren't any conflicting folder names in your hadoop directory (for me it was /usr/local/hadoop).

When I was generating output, I was putting it in a folder called output/, however prior to this program I had another that was also writing to output, and I had saved the output data in a folder specifically called output in my hadoop directory. This was causing problems for me, since even though that folder didn't show up when I ran bin/hadoop fs -ls, the command bin/hadoop fs -cat output/* was actually searching in the folder that I had generated before, instead of the output of the program that I had just run. After deleting that output directory with rm -rf output/, the problem went away.

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