Hadoop JAVA_HOME is not set error

Most first time users of Hadoop are facing this problem. I thought it is better to write a note on this topic. JAVA_HOME is environment variable that Hadoop needs and most Linux users confuse with word “environment variable”. Linux environment variables can be set in many ways (.bashrc, .bash_profile etc) but hadoop is not looking for this. There is file under hadoop_installation_path/conf/hadoop-env.sh. Open it in edit mode and you should see a line starting with # export JAVA_HOME=.... change its value to the location where you have installed your Java and remove the # in front of the line. You should be able to run Hadoop. Drop a comment if you still face an issue.