brew install hadoop

etc/hadoop/mapred-site.xml

<configuration>
     <property>
         <name>mapred.job.tracker</name>
         <value>localhost:9001</value>
     </property>
</configuration>

etc/hadoop/core-site.xml

<configuration>
    <property>
        <name>fs.defaultFS</name>
        <value>hdfs://localhost:9000</value>
    </property>
</configuration>

etc/hadoop/hdfs-site.xml

<configuration>
    <property>
        <name>dfs.replication</name>
        <value>1</value>
    </property>
</configuration>

$ hdfs namenode -format # format file system
$ start-dfs.sh
$ start-yarn.sh
$ hdfs dfs -mkdir input
$ hdfs dfs -rm -r input
$ # transfer files to input for testing
$ hdfs dfs -put /usr/local/Cellar/hadoop/2.7.2/libexec/etc/hadoop/ input
$ hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.2.jar wordcount input output