Working With Hadoop: localhost: Error: JAVA_HOME is not set

Question

I\'m working with Ubuntu 12.04 LTS.

I\'m going through the hadoop quickstart manual to make a pseudo-distributed operation. It seems simple and straightforward (eas

Answer 1

extract from etc/hadoop/hadoop-env.sh

The only required environment variable is JAVA_HOME. All others are optional. When running a distributed configuration it is best to set JAVA_HOME in this file, so that it is correctly defined on remote nodes.

This means its better and advised to set JAVA_HOME here.. even though the existing definition reads the JAVA_HOME variable. Perhaps its not getting the value of JAVA_HOME from previously set value... standard apache manual does not tell this :( :(

Answer 2

Change the JAVA_HOME variable in conf/hadoop-env.sh

export JAVA_HOME=/etc/local/java/<jdk folder>

Answer 3

echo "export JAVA_HOME=/usr/lib/java" >> $HADOOP_HOME/etc/hadoop/hadoop-env.sh

Notice: Do not use export JAVA_HOME=${JAVA_HOME} !

Answer 4

I am using hadoop 1.1, and faced the same problem.

I got it solved through changing JAVA_HOME variable in /etc/hadoop/hadoop-env.sh as:

export JAVA_HOME=/usr/lib/jvm/<jdk folder>

Answer 5

This error is coming from Line 180

if [[ -z $JAVA_HOME ]]; then
   echo "Error: JAVA_HOME is not set and could not be found." 1>&2
   exit 1
fi

in libexec/hadoop-config.sh.

Try echo $JAVA_HOME in that script. If it doesn't recognize,

Find your JAVA_HOME using this:

$(readlink -f /usr/bin/javac | sed "s:/bin/javac::")

and replace the line

export JAVA_HOME=${JAVA_HOME} in /etc/hadoop/hadoop-env.sh with JAVA_HOME you got from above command.

Answer 6

I also had faced the similar problem in hadoop 1.1 I had not noticed that the JAVA_HOME was commented in: hadoop/conf/hadoop-env.sh

It was

/#JAVA_HOME=/usr/lib/jvm/java-6-oracle

Had to change it to

JAVA_HOME=/usr/lib/jvm/java-6-oracle