Determining the correct path for JAVA_HOME is a bit complex on an Ubuntu system because it uses alternatives. On my machine this is how alternatives creates at least two levels of indirection before it gets to the actual java or javac.
usr/bin/javac -> /etc/alternatives/
/etc/alternatives/java -> /usr/lib/jvm/jdk1.7/bin/javac
If I set JAVA_HOME to /usr/lib/jvm/jdk1.7 , then it is possible that my system java might become inconsistent with the java pointed to by JAVA_HOME, if I update alternatives to use another java.
My question is, what is the correct value for JAVA_HOME on a system that uses alternatives. I am inclined to think that JAVA_HOME should be set to /usr
This way TOMCAT or any other software that uses it, will append ‘bin’ to JAVA_HOME and find all the executables it needs.
Is this the correct value for JAVA_HOME on systems that use alternatives. Do most software use JAVA_HOME only to locate the executables, or would they use the value to locate other artifacts (such as the security policy fil, etc) that come bundled with the JDK ? If the former is true, then I feel we can use /usr for JAVA_HOME, but if the latter is true, then I think the only way to use JAVA_HOME correctly is by sacrificing the alternatives functionality.
Good question – I use “alternatives” on Linux and everything “just works” – I never really had to think about it.
I believe this is the answer:
JAVA_HOME=/usr/lib/jvm/default-javaWhat is the correct target for the JAVA_HOME envrionment variable for a Linux OpenJDK Debian-based distribution?
1) “alternatives” sets the symlink to whatever your “real” Java is currently configured to
2) All you need to do is set $JAVA_HOME to the symlink