in this example I am upgrading from Java 1.4 to 1.6
if java is available in your repository type
yum update java or if you have the rpm
type rpm -Uvh java-version_of_yourJava.i386.rpm
Although upgrade option is used in both instances, java is not actually upgraded. Just the new version is installed alongside your current version.
You need to use the alternatives system to use the new version. here's how. type alternatives --config java
The alternatives system maintains symbolic links determining default commands. Our new version of java is installed under
/usr/java/jdk1.6.0_26 (so the path of java binary is /usr/java/jdk1.6.0_26/bin/java. I’ll add this as the default for Java:
type
alternatives --config java
You should receive output similar to the following:
There is 1 program which provide 'java'.
Selection Command
-----------------------------------------------
* 1 /usr/lib/jvm/jre-1.4.2-gcj/bin/java
Enter to keep the current selection[+], or type selection number:
As you can see the new version of Java is not only not being used, but there is no mention of it in the alternatives system.
So we need to add it to the alternatives system to be able to use it. heres how. type
alternatives --install /usr/bin/java java /usr/java/jdk1.6.0_43/bin/java 1
The syntax of alternatives is as following
-- install /path_to_symlink program_name /path_to_program priority
Once done if you type
alternatives --config java
You should now get the following
There are 2 programs which provide 'java'.
Selection Command
-----------------------------------------------
* 1 /usr/lib/jvm/jre-1.4.2-gcj/bin/java
+ 2 /usr/java/jdk1.6.0_43/bin/java
Enter to keep the current selection[+], or type selection number:
Simply select the version that you want to use as the default version.
Select 2 to use the new 1.6 version.
You can switch between versions this way and change back to the old version if you need to.
