How to install JRE (the Java Runtime Environment) from Java.com

If a browser plugin and Java runtime are all that is required, as opposed to a full Java development environment, the Oracle (formerly Sun) Java Runtime Environment (JRE) RPMs work for all currently supported CentOS versions, and are arguably the most compatible with web pages that require a Java plugin. The Java versions shown below are current as of this writing. Always use the latest available version for your architecture (i386 32-bit or x86_64/amd64 64-bit) and adjust accordingly.

Download the latest Linux RPM (self-extracting file), currently jre-6u30-linux-i586-rpm.bin, from java.com then as root install and configure the alternatives system and plugins:

# cd [download directory]
# sh ./jre-6u30-linux-i586-rpm.bin
# alternatives --config java
There are 2 programs which provide 'java'.
 Selection Command
-----------------------------------------------
*+ 1 /usr/lib/jvm/jre-1.6.0-openjdk/bin/java
 2 /usr/lib/jvm/jre-1.5.0-gcj/bin/java
Enter to keep the current selection[+], or type selection number:

Note number of versions, N, and use N+1 (if there is no output from the previous command, just imagine that N=0) - For example, if 2 versions were installed then:

# alternatives --install /usr/bin/java java /usr/java/latest/bin/java 3
# alternatives --config java
There are 3 programs which provide 'java'.
 Selection Command
-----------------------------------------------
*+ 1 /usr/lib/jvm/jre-1.6.0-openjdk/bin/java
 2 /usr/lib/jvm/jre-1.5.0-gcj/bin/java
 3 /usr/java/latest/bin/java
Enter to keep the current selection[+], or type selection number: 3
# java -version
java version "1.6.0_30"
Java(TM) SE Runtime Environment (build 1.6.0_30)
Java HotSpot(TM) Client VM (build 20.1-b02, mixed mode, sharing)

Create links in the Mozilla Plugins directory so Java will work in supported browsers such as Firefox.

# cd /usr/lib/mozilla/plugins/
# ln -fs /usr/java/latest/lib/i386/libnpjp2.so
</code sh>

Skip to the section on testing the browser plugin. 

===== Java x86_64 JRE and plugin =====

Download the latest Linux RPM (self-extracting file), currently jre-6u30-linux-x64-rpm.bin, from [[http://www.java.com/en/download/linux_manual.jsp|java.com]] then as root install and configure the alternatives system and plugins: 

<code sh>
# cd [download directory]
# sh ./jre-6u30-linux-x64-rpm.bin
# alternatives --config java
There are 4 programs which provide 'java'.
 Selection Command
-----------------------------------------------
 1 /usr/lib/jvm/jre-1.4.2-gcj/bin/java
 2 /usr/java/jre1.6.0_13/bin/java
 3 /usr/java/jre1.6.0_18/bin/java
*+ 4 /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java
Enter to keep the current selection[+], or type selection number:

Note number of versions, N, and use N+1 (if there is no output from the previous command, just imagine that N=0) - For example, if 4 versions were installed then:

# alternatives --install /usr/bin/java java /usr/java/latest/bin/java 5
# alternatives --config java
There are 5 programs which provide 'java'.
 Selection Command
-----------------------------------------------
 1 /usr/lib/jvm/jre-1.4.2-gcj/bin/java
 2 /usr/java/jre1.6.0_13/bin/java
 3 /usr/java/jre1.6.0_18/bin/java
*+ 4 /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java
 5 /usr/java/latest/bin/java
Enter to keep the current selection[+], or type selection number: 5
# java -version
java version "1.6.0_26"
Java(TM) SE Runtime Environment (build 1.6.0_30)
Java HotSpot(TM) 64-Bit Server VM (build 20.1-b02, mixed mode)

Create links in the Mozilla Plugins directory so Java will work in supported browsers such as Firefox.

# cd /usr/lib64/mozilla/plugins/
# ln -fs /usr/java/latest/lib/amd64/libnpjp2.so

Exit Firefox if it is running and [re]start Firefox. Type «about:plugins» in the URL field. It should show Java enabled.

Verify installed version at Java.com, Test installed version at Java.com or at javatester.org.

Oracle recommends removing old Java versions as they represent a security risk if left installed. By default, the installation procedure above will not remove old versions so we must do this manually:

# rpm -qa jre\*
jre-1.6.0_13-fcs.x86_64
jre-1.6.0_18-fcs.x86_64
jre-1.6.0_30-fcs.x86_64
# rpm -e jre-1.6.0_18-fcs.x86_64 jre-1.6.0_13-fcs.x86_64