hadoop installation in ubuntu

 sudo apt update

sudo apt upgrade -y

sudo apt install openjdk-11-jdk -y

sudo apt install openjdk-11-jdk -y

java -version

nano ~/.bashrc

export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64
export PATH=$PATH:$JAVA_HOME/bin

source ~/.bashrc

sudo apt install ssh -y

ssh-keygen -t rsa -P ""
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
ssh localhost

cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys

sudo apt dist-upgrade -y

sudo do-release-upgrade

wget https://downloads.apache.org/hadoop/common/hadoop-3.3.6/hadoop-3.3.6.tar.gz

tar -xvzf hadoop-3.3.6.tar.gz
sudo mv hadoop-3.3.6 /usr/local/hadoop
sudo chown -R $USER:$USER /usr/local/hadoop

nano ~/.bashrc

Add at bottom:

export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64
export HADOOP_HOME=/usr/local/hadoop
export PATH=$PATH:$HADOOP_HOME/bin:$HADOOP_HOME/sbin


source ~/.bashrc

hadoop version

nano /usr/local/hadoop/etc/hadoop/hadoop-env.sh

# export JAVA_HOME=

Replace with:
export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64

/usr/local/hadoop/etc/hadoop


🔹 core-site.xml
nano core-site.xml

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


🔹 hdfs-site.xml
nano hdfs-site.xml

IMPORTANT: Use full path (NO $USER)
<property>
  <name>dfs.replication</name>
  <value>1</value>
</property>

<property>
  <name>dfs.namenode.name.dir</name>
  <value>file:///home/ubuntu/hdfs/namenode</value>
</property>

<property>
  <name>dfs.datanode.data.dir</name>
  <value>file:///home/ubuntu/hdfs/datanode</value>
</property>

⚠️ Replace ubuntu if your username is different.

🔹 mapred-site.xml
cp mapred-site.xml.template mapred-site.xml
nano mapred-site.xml

Add:
<property>
  <name>mapreduce.framework.name</name>
  <value>yarn</value>
</property>


🔹 yarn-site.xml
nano yarn-site.xml

Add:
<property>
  <name>yarn.nodemanager.aux-services</name>
  <value>mapreduce_shuffle</value>
</property>


 STEP 9 — Create Hadoop Directories (Correct Location)
mkdir -p /home/ubuntu/hdfs/namenode
mkdir -p /home/ubuntu/hdfs/datanode

Do NOT create in /root

Do NOT use $USER

STEP 10 — Format NameNode
hdfs namenode -format

You must see:
Storage directory ... has been successfully formatted


 STEP 11 — Start Hadoop
start-dfs.sh
start-yarn.sh


 STEP 12 — Verify Services
jps

You should see: