java - Setting the JAVA_HOME environment variable in Ubuntu

Question

I'm pretty new on ubuntu, at some point in the terminal I'm running:

mortar local:illustrate pigscripts/retail-recsys.pig purchase_input -f params/retail.params

but I have this following error:

A suitable java installation could not be found. If you already have java installed
please set your JAVA_HOME environment variable before continuing. Otherwise, a suitable java installation will need to be added to your local system.

Installing Java

On OSX run javac from the command line. This will intiate the installation. For Linux systems please consult the documentation on your relevant package manager.

But I'm pretty sure I have Java, so please how can I set my JAVA_HOME environment variable?

Answer 1

First, you need to decide which installed version of Java to use? No fear, you can pick any you have -

update-java-alternatives -l

One "easy" solution is to add this to "$HOME/.bashrc",

export JAVA_HOME=$(update-java-alternatives -l | head -n 1 | awk -F ' ' '{print $NF}')

This picks the first installed JDK and takes it's JAVA_HOME (the third field) - on my system that's

/usr/lib/jvm/java-1.7.0-openjdk-amd64