src/contrib/streaming/build.xml

<?xml version="1.0"?>

<project name="streaming" default="jar">

  <import file="../build-contrib.xml"/>

  <!-- Override jar target to specify main class -->
  <target name="jar" depends="compile">
    <jar
      jarfile="${build.dir}/hadoop-${name}.jar"
      basedir="${build.classes}"      
    >
  	<manifest>
	    <attribute name="Main-Class" value="org.apache.hadoop.streaming.HadoopStreaming"/>
	</manifest>
    </jar>
  </target>
  
</project>