What exactly does this Hadoop command performed in the shell? -

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i absolutly new in apache hadoop , following video course.

so have correctly installed hadoop 1.2.1 on linux ubuntu virtual machine.

after installation instructor perform command in shell:

bin/hadoop jar hadoop-examples-*.jar grep input output 'dfs[a-z.]+'

to see hadoop working , correctly installed.

but command?

this command runs grep job defined inside hadoop examples jar file (containing map, reduce , driver code) input folder search specified in input folder in hdfs while output folder output after searching patter in file while dfs[a-z.]+ regular expression saying grep in input.


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