Hadoop distribution provides a Java utility called Hadoop Streaming. It is packaged in a jar file. With Hadoop Streaming, we can create and run Map Reduce jobs with an executable script.
We can create executable scripts for Mapper and Reducer functions. These executable scripts are passed to Hadoop Streaming in a command.
Hadoop Streaming utility creates Map and Reduce jobs and submits these to a cluster. We can also monitor these jobs with this utility.Read the full book at www.amazon.com