Java is a programming language which is used on lots of websites, applications & requires java to be installed on system in order for them to completely work on the system. It comes in two packages, JDK(Java Development Kit) & JRE (Java runtime environment). JDK is used for development, monitoring &deploying  purposes& also contains JRE packages while JRE is used for deploying java application s only.

In this tutorial, we are going  to install java 7 & 8 on CentOS/RHEL 7 machines.

(Recommended Read:Complete guide for Apache TOMCAT installation on Linux )

 

Installing Java 7

We can either use yum or download a rpm package for installing  java 7 on the machine. To install java 7 using yum, run

$ yum install java-1.7.0-openjdk-devel

& to install java using rpm, we need to download rpm package for java 7. Run the following command to download rpm file for version 7,

$ wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" http://download.oracle.com/otn-pub/java/jdk/7u80-b15/jdk-7u80-linux-x64.rpm

Once rpm package has been downloaded, install it by running

$ rpm –ivh jdk-7u80-linux-x64.rpm

 

Installing Java 8

For installing java 8, we need to get the rpm package . Run the following to obtain the package,

$ wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" http://download.oracle.com/otn-pub/java/jdk/8u112-b15/jdk-8u112-linux-x64.rpm

& install it using rpm command, as we did above,

$ rpm –ivh jdk-8u112-linux-x64.rpm

(Recommended read: RPM commands with example)

Note :- After installation of java, we check the version by running

$ java –version

 

Setting Java Environment variables

Java variables, mainly JAVA_HOME & JRE_HOME, are used by many java applications to determine which java executable to use. So we need to set these variables as environment variables.  To do so, we can run,

$ JAVA_HOME=/usr/java/jdk1.7.0_05
$ export JAVA_HOME
$ PATH=$JAVA_HOME/bin:$PATH
$ export PATH

But these variables will saved for current session only & will need to configured after every reboot. To set them permanently permanantly add them to .bashrc file

$ vi .bashrc
$ JAVA_HOME=/usr/java/jdk1.7.0_05
$ PATH=$JAVA_HOME/bin:$PATH

Similarly we can add JRE_HOME variable  to the file.

Note- Change the home path & version number as per your installation.

So this completes our tutorial. Please leave any queries in the comment section below.

 

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