Reference :
Set Environment variables - PATH, CLASSPATH, JAVA_HOME, ANT_HOME in Ubuntu
Setting Environment variables in Ubuntu can be tricky. It comes with OpenOffice which requires OpenJDK, so the path for java is set to that of OpenJDK. The command
$ java -version
works but uses the OpenJDK. Once you have installed Sun JDK the location of the JDK should be "/usr/lib/jvm/java-6-sun-1.6.0.20" depending upon the version you have installed. Once you have installed it you may want to update the PATH, CLASSPATH variables and create environment variables like JAVA_HOME, ANT_HOME, etc.
The location to set up the environment variables in Ubuntu is /home/Your_User_Name/.bashrc. You will need to make entries like:
JAVA_HOME=/usr/lib/jvm/java-6-sun-1.6.0.20 ANT_HOME=/home/harkiran/javaTools/apache-ant-1.8.1 PATH=$PATH:$ORACLE_HOME/bin:$JAVA_HOME/bin:$ANT_HOME/bin CLASSPATH=.:/usr/lib/jvm/java-6-sun-1.6.0.20/lib export JAVA_HOME export ANT_HOME export CLASSPATH export PATH
The separator to use in Linux between PATH is ":" (colon). Windows uses ";" (semi colon).
Once you have set this up you will also need to create symbolic links in the "/etc/alternatives" directory. You will need administrative privileges to do so.
$ ln -s /usr/lib/jvm/java-6-sun-1.6.0.20/bin/java /etc/alternatives/java $ ln -s /usr/lib/jvm/java-6-sun-1.6.0.20/bin/javac /etc/alternatives/javac
Once done you can check using the commands java -version, javac -version, ant to check all is working and has been set up properly.
