Many Java applications that use shell scripts to configure their environment use the JAVA_HOME environment variable to start the correct version of Java, locate JRE JARs, and so on.
In macOS X 10.6, the following paths seem to be valid for this variable
/Library/Java/Home
/System/Library/Frameworks/JavaVM.framework/Home
/System/Library/Frameworks/JavaVM.framework/Versions/Current
Some of these are symlinks to the actual current VM (as defined in the Java Preference pane).
But which one should be used—or is it okay to use any of them?
I just set JAVA_HOME to the output of that command, which should give you the Java path specified in your Java preferences. Here's a snippet from my .bashrc file, which sets this variable:
export JAVA_HOME=$(/usr/libexec/java_home)
I haven't experienced any problems with that technique.
Occasionally I do have to change the value of JAVA_HOME to an earlier version of Java. For example, one program I'm maintaining requires 32-bit Java 5 on OS X, so when using that program, I set JAVA_HOME by running:
export JAVA_HOME=$(/usr/libexec/java_home -v 1.5)
For those of you who don't have java_home in your path add it like this.
sudo ln -s /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java_home /usr/libexec/java_home
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