A system-wide way to set or get $JAVA_HOME in Ubuntu?

Question

I wonder whether Ubuntu itself provides a system-wide way to find the current JAVA_HOME or whether there is right place for setting JAVA_HOME.

Mac OS X does well in this, for /usr/libexec/java_home command returns the current JAVA_HOME. But to Ubuntu, the materials I found always told me to set the $JAVA_PATH pointing to a static path like ```, which is stored in~/.bash_profile```.

I think, however, this approach has several drawbacks:

1. Once Java updates, the mini version number will change, which makes the static path no longer available.
2. After changing the JRE used in my system with update-alternatives, I have to modify $JAVA_HOME in .bash_profile. That extra work is annoying.
3. Some $JAVA_HOME-required programs, is not aware of .bash_profile at all. I have to set $JAVA_HOME in their start-up script, therefore a standard-and-easy way to get $JAVA_HOME seems critical to me.

Well, any advice is welcomed. Thanks.

Answer 1

A little hacky, but put this line in your /etc/profile for setting it system-wide:

export JAVA_HOME=$(dirname $(dirname $(readlink -e /usr/bin/javac)))

Answer 2

You can set environment variables in /etc/environment, which gets setup by PAM. There should also be symlinks in /usr/lib/jvm which don't change with minor releases.

JAVA_HOME=/usr/lib/jvm/java-6-sun