Some Java programs need the environment variable JAVA_HOME, such as Tomcat. In Windows operating system, JAVA_HOME is the directory that the JDK is located. However, in Ubuntu if you install JDK with “sudo apt-get install sun-java6-jdk”, the JDK’s files are extracted to many directories like /usr/bin, /usr/lib, etc. What is JAVA_HOME?
Some people thought it should be /usr because in Windows the Java compiler “javac” is in JAVA_HOMEbinjavac. So in Linux it should be JAVA_HOMEbinjavac and JAVA_HOME=/usr. I don’t think it is the best sulotion. Because I found /usr/bin/javac is not the real Java compiler, it is just a link. I used “ls -l /usr/bin/javac” to see what it links to:
/usr/bin/javac -> /etc/alternatives/javac
And /etc/alternatives/javac is also a link. It links to /usr/lib/jvm/java-6-sun/bin/javac. This is the real Java compiler. And the path is similar to that in Windows. So I think JAVA_HOME should be /usr/lib/jvm/java-6-sun in Ubuntu Linux.