Hadoop Commands

This section describes the Hadoop commands.

All Hadoop commands are invoked by the bin/hadoop script. When you run these commands, you can specify the MapReduce mode in two different ways:

  • Use the hadoop keyword and specify the mode explicitly, where classic mode refers to Hadoop 1.x and yarn mode refers to Hadoop 2.x.
  • Use the hadoop1 or hadoop2 keyword and do not specify the mode.

For example, the following commands are equivalent:

root@testnode100:/opt/mapr/conf/conf.d# hadoop2 conf | grep mapreduce.map.memory.mb
<property><name>mapreduce.map.memory.mb</name><value>1024</value></property>

root@testnode100:/opt/mapr/conf/conf.d# hadoop -yarn conf | grep mapreduce.map.memory.mb
<property><name>mapreduce.map.memory.mb</name><value>1024</value></property>