Hadoop Commands

Hadoop commands enable the interaction with the Apache Hadoop software in order to work with big data using the map-reduce paradigm. This article presents some of the most important commands for Hadoop below. Please find more details about HDFS commands in our article Hadoop FS Commands.

Start and Stop YARN
The YARN scheduler is one key element of the Apache Hadoop. The following command can be used to start YARN as follows:

$ start-yarn.sh
Output:

starting yarn daemons
starting resourcemanager, logging to /home/ubuntu/hadoop-2.8.0/logs/yarn-ubuntu-resourcemanager-i-3992cc97.out
localhost: starting nodemanager, logging to /home/ubuntu/hadoop-2.8.0/logs/yarn-ubuntu-nodemanager-i-3992cc97.out

If there are no critical error messages we can confirm that YARN is started and can be used. YARN can be stopped using the following command below.

$ stop-yarn.sh
Output:

stopping yarn daemons
stopping resourcemanager
resourcemanager did not stop gracefully after 5 seconds: killing with kill -9
localhost: stopping nodemanager
localhost: nodemanager did not stop gracefully after 5 seconds: killing with kill -9
no proxyserver to stop

Hadoop Commands Details

The following interesting video shows some more details about this topic: