Oracle puts out JDK updates every now and then. The Linux update comes in the binary form (for install in any directory) and RPM form. I like RPM format because it plugs into OS's standard package installation mechanism. So I downloaded the RPM from
here and installed it using:
> chmod u+x jdk-6u31-linux-x64-rpm.bin
> ./jdk-6u31-linux-x64-rpm.bin
:
:
:
and went to command line and typed:
> java -version
java version "1.4.2"
gij (GNU libgcj) version 4.1.2 20080704 (Red Hat 4.1.2-48)
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Huh? I had presumed that installing the RPM will do the right thing. Uh uh.
Sure enough:
> ls -l /usr/bin/java
lrwxrwxrwx 1 root root 22 Apr 13 11:35 /usr/bin/java -> /etc/alternatives/java
> ls -l /etc/alternatives/java
lrwxrwxrwx 1 root root 30 Apr 13 14:13 /etc/alternatives/java -> /usr/lib/jvm/jre-1.4.2-gcj/bin/java
revealed that java command was linked to jre-1.4.2-gcj java.
Apparently you have to run the following commands to make the newly installed java and javac as available alternatives.
> update-alternatives --install /usr/bin/java java /usr/java/jdk1.6.0_31/bin/java 3000
> update-alternatives --install /usr/bin/javac javac /usr/java/jdk1.6.0_31/bin/javac 3000
Now to see what all Java alternatives are available you can run:
> update-alternatives --display java
java - status is manual.
link currently points to /usr/lib/jvm/jre-1.4.2-gcj/bin/java
/usr/lib/jvm/jre-1.4.2-gcj/bin/java - priority 1420
slave keytool: /usr/lib/jvm/jre-1.4.2-gcj/bin/keytool
slave rmiregistry: /usr/lib/jvm/jre-1.4.2-gcj/bin/rmiregistry
slave jre_exports: /usr/lib/jvm-exports/jre-1.4.2-gcj
slave jre: /usr/lib/jvm/jre-1.4.2-gcj
/usr/java/jdk1.6.0_31/bin/java - priority 3000
slave keytool: (null)
slave rmiregistry: (null)
slave jre_exports: (null)
slave jre: (null)
Current `best' version is /usr/java/jdk1.6.0_31/bin/java.
And finally to select which java to use - use the command:
> update-alternatives --config java
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_31/bin/java
Enter to keep the current selection[+], or type selection number: 2
Select the one from the list and type ENTER. Then do:
> update-alternatives --config javac
:
:
and viola! Now the system will use the Java you selected.
Hope this helps you!
