install and setup JAVA JDK in CentOS 6

1. The first thing I've done was to make sure the CentOS 6 system is fully up-to-date, so I ran

yum update

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2. Once the update completed, I then checked the system for any other installed JAVA packages using

rpm -qa | grep -E '^open[jre|jdk]|j[re|dk]'

there was the java-1.6.0-openjdk-1.6.0.0-1.56.1.11.8.el6_3.i686 package already installed so I removed it by running

yum remove java-1.6.0-openjdk

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3. The next step was to go and download the required JAVA JDK package for the system I was working on. It was a 32 bit CentOS 6 so I needed to get the 32 bit JAVA JDK package from Oracle's JAVA download page

Note that I needed to install an older version of JAVA JDK since it was specific to the software I was setting up.
Download JAVA JDK6 here
Download JAVA JDK7 here

You may also wget Oracle JDK 7 using command line as in
JAVA JDK 7
for 64bit (x86_64) system

wget --no-cookies \
--header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com" \
"http://download.oracle.com/otn-pub/java/jdk/7u45-b18/jdk-7u45-linux-x64.rpm" \
-O /opt/jdk-7u45-linux-x64.rpm --no-check-certificate

for 32bit (x86) system

wget --no-cookies \
--header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com" \
"http://download.oracle.com/otn-pub/java/jdk/7u45-b18/jdk-7u45-linux-i586.rpm" \
-O /opt/jdk-7u45-linux-i586.rpm --no-check-certificate

JAVA JDK 6

for 64bit (x86_64) system

wget --no-cookies \
--header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com" \
"http://download.oracle.com/otn/java/jdk/6u45-b06/jdk-6u45-linux-x64-rpm.bin" \
-O /opt/jdk-6u45-linux-x64-rpm.bin --no-check-certificate

for 32bit (x86) system

wget --no-cookies \
--header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com" \
"http://download.oracle.com/otn/java/jdk/6u45-b06/jdk-6u45-linux-i586-rpm.bin" \
-O /opt/jdk-6u45-linux-i586-rpm.bin --no-check-certificate

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4. Once the JAVA JDK package got downloaded I proceeded with installing the package.

a) Installing the JAVA JDK6 package in CentOS 6

chmod +x /opt/jdk-6u45-linux-i586-rpm.bin
/opt/./jdk-6u45-linux-i586-rpm.bin

b) Installing the JAVA JDK7 package in CentOS 6

rpm -Uvh /opt/jdk-7u45-linux-i586.rpm

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5. Once the JAVA JDK package is installed, I then needed to configure it on the system using the alternatives command. This is in order to tell the system what are the default commands for JAVA. Most sys admins aren't aware about this and I think that it is a vital part when setting the JAVA package

a) Setting up the JAVA JDK6 package

alternatives --install /usr/bin/java java /usr/java/jdk1.6.0_45/jre/bin/java 20000
alternatives --install /usr/bin/jar jar /usr/java/jdk1.6.0_45/bin/jar 20000
alternatives --install /usr/bin/javac javac /usr/java/jdk1.6.0_45/bin/javac 20000
alternatives --install /usr/bin/javaws javaws /usr/java/jdk1.6.0_45/jre/bin/javaws 20000
alternatives --set java /usr/java/jdk1.6.0_45/jre/bin/java
alternatives --set javaws /usr/java/jdk1.6.0_45/jre/bin/javaws
alternatives --set javac /usr/java/jdk1.6.0_45/bin/javac
alternatives --set jar /usr/java/jdk1.6.0_45/bin/jar

this set the default commands for JAVA JDK7 and listing the /etc/alternatives/ directory showed the following

ls -lA /etc/alternatives/
lrwxrwxrwx. 1 root root 29 Feb 22 03:39 jar -> /usr/java/jdk1.6.0_45/bin/jar
lrwxrwxrwx. 1 root root 34 Feb 22 03:39 java -> /usr/java/jdk1.6.0_45/jre/bin/java
lrwxrwxrwx. 1 root root 31 Feb 22 03:39 javac -> /usr/java/jdk1.6.0_45/bin/javac
lrwxrwxrwx. 1 root root 36 Feb 22 03:39 javaws -> /usr/java/jdk1.6.0_45/jre/bin/javaws

b) Setting up the JAVA JDK7 package

alternatives --install /usr/bin/java java /usr/java/jdk1.7.0_45/jre/bin/java 20000
alternatives --install /usr/bin/jar jar /usr/java/jdk1.7.0_45/bin/jar 20000
alternatives --install /usr/bin/javac javac /usr/java/jdk1.7.0_45/bin/javac 20000
alternatives --install /usr/bin/javaws javaws /usr/java/jdk1.7.0_45/jre/bin/javaws 20000
alternatives --set java /usr/java/jdk1.7.0_45/jre/bin/java
alternatives --set javaws /usr/java/jdk1.7.0_45/jre/bin/javaws
alternatives --set javac /usr/java/jdk1.7.0_45/bin/javac
alternatives --set jar /usr/java/jdk1.7.0_45/bin/jar

this set the default commands for JAVA JDK7 and listing the /etc/alternatives/ directory showed the following

ls -lA /etc/alternatives/
lrwxrwxrwx. 1 root root 29 Feb 22 03:39 jar -> /usr/java/jdk1.7.0_45/bin/jar
lrwxrwxrwx. 1 root root 34 Feb 22 03:39 java -> /usr/java/jdk1.7.0_45/jre/bin/java
lrwxrwxrwx. 1 root root 31 Feb 22 03:39 javac -> /usr/java/jdk1.7.0_45/bin/javac
lrwxrwxrwx. 1 root root 36 Feb 22 03:39 javaws -> /usr/java/jdk1.7.0_45/jre/bin/javaws

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6. Finally I verified the installed version of JAVA

java -version
java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) Client VM (build 24.45-b08, mixed mode, sharing)

I know this how-to will serve me as a quick reference for installing Oracle JAVA in the future and I truly hope this will help someone else too.

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