JRUBY installation from Ubuntu

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How to Install JRuby on Ubuntu — A Complete Beginner‑Friendly Guide

If you’re exploring the Ruby ecosystem but want the power, performance, and JVM compatibility of Java, JRuby is the perfect choice. JRuby is a high‑performance Ruby implementation built on top of the Java Virtual Machine (JVM), making it ideal for enterprise applications, integrations, and high‑throughput systems.

In this blog, I’ll walk you through the JRuby installation process on Ubuntu, along with the prerequisites, verification steps, and common troubleshooting tips.

What is JRuby?

JRuby is an alternative Ruby interpreter that runs on the Java Virtual Machine (JVM). It gives you the flexibility of Ruby with the performance and scalability of Java.

Why JRuby?

  • Runs Ruby code on the JVM

  • Integrates with Java libraries

  • Better performance for multi‑threaded applications

  • Ideal for enterprise‑level deployments

  • Works well with tools like Rake, Rails, and Bundler

If you’re already working with Java or JVM‑based systems, JRuby becomes a natural fit.

Step 1: Update Your Ubuntu System

Before installing anything, update your package list:

bash
sudo apt update
sudo apt upgrade -y

This ensures you’re working with the latest repositories.

Step 2: Install Java (JDK)

JRuby requires Java because it runs on the JVM. Install OpenJDK:

bash
sudo apt install openjdk-17-jdk -y

Verify the installation:

bash
java -version

You should see something like:

Code
openjdk version "17.x.x"

Step 3: Download JRuby

You can download JRuby using wget:

bash
wget https://repo1.maven.org/maven2/org/jruby/jruby-dist/9.4.5.0/jruby-dist-9.4.5.0-bin.tar.gz

(Version numbers may change — always check the official JRuby website for the latest release.)

Step 4: Extract the JRuby Package

Extract the downloaded file:

bash
tar -xvzf jruby-dist-9.4.5.0-bin.tar.gz

Move it to /opt (a common location for custom software):

bash
sudo mv jruby-9.4.5.0 /opt/jruby

Step 5: Add JRuby to Your PATH

Open your .bashrc or .zshrc file:

bash
nano ~/.bashrc

Add the following lines at the bottom:

bash
export JRUBY_HOME=/opt/jruby
export PATH=$PATH:$JRUBY_HOME/bin

Reload the file:

bash
source ~/.bashrc

Step 6: Verify JRuby Installation

Run:

bash
jruby -v

You should see something like:

Code
jruby 9.4.x (Ruby 3.x compatible) on Java 17

This confirms JRuby is installed and working.

Step 7: Install RubyGems (Optional but Recommended)

JRuby comes with RubyGems built‑in, but you can update it:

jruby -S gem update --system

Install Bundler:

jruby -S gem install bundler

Step 8: Run a Simple JRuby Program

Create a file:

bash
nano test.rb

Add:

ruby
puts "JRuby is working on Ubuntu!"

Run it:

jruby test.rb

If you see the output, your JRuby setup is complete.

Common Issues & Fixes

1. “jruby: command not found”

Your PATH variable is not updated. Re‑check .bashrc and run:

source ~/.bashrc

2. Java version mismatch

JRuby works best with Java 11 or Java 17. Switch Java versions using:

sudo update-alternatives --config java

3. Permission issues

If JRuby is installed in /opt, ensure correct permissions:

sudo chmod -R 755 /opt/jruby

Final Thoughts

Installing JRuby on Ubuntu is straightforward once you understand the dependencies and environment setup. With JRuby, you get the flexibility of Ruby combined with the robustness of the JVM — a powerful combination for modern development.

Whether you're building microservices, scripting automation, or integrating with Java systems, JRuby gives you a strong foundation.


Note: Image downloaded from Google

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