make Sun's java the default in ubuntu

October 7th, 2007
Okay, so you installed all required packages to get Sun's JRE and/or JDK in your Ubuntu box, but when you try to run a java program you don't get Sun's jvm.

To see what jvm is your current default, run this command:

~$ ls -l /etc/alternatives/java
lrwxrwxrwx 1 root root 34 2007-10-06 07:40
/etc/alternatives/java → /usr/lib/jvm/java-gcj/jre/bin/java


In this example we see that we are currently using gcj.

To change the default jvm, run this command:

$ sudo update-alternatives --config java

You will be presented a menu with all the available jvms, and you will be prompted to choose your new default:

$ sudo update-alternatives --config java
Password: *******

There are 3 alternatives which provide `java'.

Selection Alternative
--------------------------------------------------------------------------------------------
1 /usr/lib/jvm/java-6-sun/jre/bin/java
2 /usr/bin/gij-wrapper-4.1
*+ 3 /usr/lib/jvm/java-gcj/jre/bin/java

Press enter to keep the default[*], or type selection number: 1
Using `/usr/lib/jvm/java-6-sun/jre/bin/java' to provide `java'.


To check if the new default is set correctly run the previous command again:

$ ls -l /etc/alternatives/java
lrwxrwxrwx 1 root root 36 2007-10-07 12:21
/etc/alternatives/java → /usr/lib/jvm/java-6-sun/jre/bin/java


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