In java -D what does the D stand for?

I've always assumed it was to define the value of a property... possibly a legacy from C compilers, which often use -D as similar to #define in code.

EDIT: The closest I have to a source for this at the moment is some JDK 1.1 documentation which specifies the flag as:

Redefines a property value. propertyName is the name of the property whose value you want to change and newValue is the value to change it to. [...]

That at least contains the word "redefine" which is close to "define" :)

Hadoop Environment Setting

# Java Environment Variables

export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64

export PATH=$PATH:$JAVA_HOME/bin

#Cassandra Environment Variables

export CASSANDRA_HOME=/usr/local/softwares/cassandra-3.11.7

export PATH=$PATH:$CASSANDRA_HOME/bin

#Spark Environment Variables

export SPARK_HOME=/usr/local/softwares/spark-2.4.6-hadoop2.7

export PATH=$PATH:$SPARK_HOME/bin

#Kafka Environment Variables

export KAFKA_HOME=/usr/local/softwares/kafka_2.12-2.4.1

export PATH=$PATH:$KAFKA_HOME/bin

#Hadop Environment Variables

export HADOOP_HOME=/usr/local/softwares/hadoop-2.8.5

export HADOOP_CONF_DIR=$HADOOP_HOME/etc/hadoop

export HADOOP_HDFS_HOME=$HADOOP_HOME

export HADOOP_INSTALL=$HADOOP_HOME

export HADOOP_MAPRED_HOME=$HADOOP_HOME

export HADOOP_COMMON_HOME=$HADOOP_HOME

export HADOOP_HDFS_HOME=$HADOOP_HOME

export YARN_HOME=$HADOOP_HOME

export HADOOP_COMMON_LIB_NATIVE_DIR=$HADOOP_HOME/lib/native

export PATH=$PATH:$HADOOP_HOME/sbin:$HADOOP_HOME/bin

export HADOOP_OPTS="-Djava.library.path=$HADOOP_HOME/lib/native"

# Hive Environment Variables

export HIVE_HOME=/usr/local/softwares/apache-hive-2.3.5

export PATH=$PATH:$HIVE_HOME/bin

To Learn hadoop Reference

http://blog.praveendeshmane.co.in/index.jsp  

HBase Error IllegalStateException when starting Master: hsync

I had similar issue while using HBase 2.2.3 with Hadoop 2.10.0 on a 3-N Hbase cluster while using HDFS as the base.rootdir.

Solution

1. Set the configuration to hbase.unsafe.stream.capability.enforce to false in hbase-site.xml

<property>

  <name>hbase.unsafe.stream.capability.enforce</name>

  <value>false</value>

</property>

1. Not sure of this was necessary , also changed the hbase.wal.dir to an HDFS directory outside the hbase.rootdir

zookeeper.ClientCnxn: Opening socket connection to server localhost/192.168.43.203:2181. Will not attempt to authenticate using SASL

Any location: local or HDFS location:

Solution : remove the /user/nagaraju/hbase

           and also remove  the /user/nagaraju/zookeeper

How to share files between Virtual Box Ubuntu and host computer

https://www.youtube.com/watch?v=TcrfrVNNGMU

Connect Oracle VM Ubuntu with Putty

Please follow the below link.

https://www.youtube.com/watch?v=9EuvlQ5XHeI 

If still you are not able to connect then we have to install   openssh-server 

Please follow the below link.

https://www.youtube.com/watch?v=KbE9VV3Yh2U