Hadoop: How can i merge reducer outputs to a single file? [duplicate]

Answer 1

You get a single Out-put File by Setting a single Reducer in your code .

Job.setNumberOfReducer(1);

Will work for your requirement , but costly

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OR

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Static method to execute a shell command. 
Covers most of the simple cases without requiring the user to implement the Shell interface.

Parameters:
env the map of environment key=value
cmd shell command to execute.
Returns:
the output of the executed command.

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org.apache.hadoop.util.Shell.execCommand(String[])