How to install Oracle Java JDK 8 on Centos 6,7

Step 1 - First of all, update your server.

Step 2 - Then, search for if any older JDK versions are installed in your system.

        root@chatserver [~]# rpm -qa | grep -E '^open[jre|jdk]|j[re|dk]'

root@chatserver [~]# rpm -qa | grep jdk

Step 3 - To check the already installed Java version, enter the following command:

        root@chatserver [~]# java -version

       -bash: java: command not found

Step 4 - If Java 1.6 or 1.7 have been installed already, you can uninstall them using the following commands.

root@chatserver [~]# yum remove java-1.6.0-openjdk

root@chatserver [~]# yum remove java-1.7.0-openjdk

root@chatserver [~]# rpm -ev jdk-8u31-linux-i586.rpm

Step 5 - Download And Install Oracle Java JDK on you PC

Go to the "Oracle Java download page" and download the required version depending upon your distribution architecture and install the java package or Use "wget".

"wget http://download.oracle.com/otn-pub/java/jdk/8u31-b13/jdk-8u31-linux-i586.rpm"

        root@chatserver [~/tmp]# cd tmp/

        root@chatserver [~/tmp]# wget http://download.oracle.com/otn-pub/java/jdk/8u31-b13/jdk-8u31-linux-i586.rpm

         root@chatserver [~/tmp]# rpm -ivh jdk-8u31-linux-i586.rpm

Step 6 - Now, check for the installed JDK version in your system using command:

        root@chatserver [~/tmp]# java -version

java version "1.8.0_31"

Java(TM) SE Runtime Environment (build 1.8.0_31-b13)

Java HotSpot(TM) Client VM (build 25.31-b07, mixed mode, sharing)

Step 7 - We can easily set the environment variables using the "export" command as shown below.

Note : This method is not recommended. Because, the path will be disappeared when the system reboots.

        root@chatserver [~/tmp]# export JAVA_HOME=/usr/java/jdk1.8.0_31/

root@chatserver [~/tmp]# export PATH=$PATH:JAVA_HOME

Step 8 - Now, let us check for the environment variables using commands:

root@chatserver [~/tmp]# echo $JAVA_HOME

/usr/java/jdk1.8.0_31/

root@chatserver [~/tmp]# echo $PATH

/usr/local/jdk/bin:/usr/java/jdk1.8.0_31//bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin:/usr/X11R6/bin:/root/bin:JAVA_HOME

Step 9 - To make it permanent, you have to add the paths in the system wide profile.To do that, create a file called java.sh under /etc/profile.d/ directory.

        root@chatserver [~]# vim /etc/profile.d/java.sh

#!/bin/bash

JAVA_HOME=/usr/java/jdk1.8.0_31/

PATH=$JAVA_HOME/bin:$PATH

export PATH JAVA_HOME

export CLASSPATH=.

Step 10 - Make it executable using command:

         root@chatserver [~]# chmod +x /etc/profile.d/java.sh

Step 11 - Then, set the environment variables permanently by running the following command:

root@chatserver [~]# source /etc/profile.d/java.sh

That’s it......