Hadoop: «ERROR : JAVA_HOME is not set»
Make sure that you have removed the comment tag and changed your JAVA_HOME in the hadoop-env.sh as well as the appropriate .bashrc and/or .profile:
# export JAVA_HOME=/usr/lib/jvm/java-1.6.0-openjdkshould be
export JAVA_HOME=/usr/lib/jvm/java-1.6.0-openjdkYou can set your JAVA_HOME and PATH for all users (make sure you haven't previously set this to the wrong path) in /etc/profile.
Also, don't forget to activate the new change by logging-out/in or by executing source /etc/profile.
You should set JAVA_HOME in the hadoop-env.sh file also which is in the Hadoop configuration directory.By default the JAVA_HOME setting line is commented.
Type echo $JAVA_HOME in your terminal to be sure your JAVA_HOME is set.
You can also type java -version to know what version of java you are actually using.
By the way, reading your description it seems your actually writing
export JAVA_HOME=/usr/lib/jvm/java-1.6.0-openjdkin the file conf/hadoop-env.sh, you should write it in your terminal or in ~/.bashrc or ~/.profile then type source < path to modified file >.