8 of the Best Free Ruby Books

1. Ruby Best Practices

Ruby Best Practices is for programmers who want to use Ruby as experienced Rubyists do. Written by the developer of the Ruby project Prawn, this book explains how to design beautiful APIs and domain-specific languages with Ruby, as well as how to work with functional programming ideas and techniques that can simplify your code and make you more productive.

Ruby Best Practices is much more about how to go about solving problems in Ruby than it is about the exact solution you should use. The book is not targeted at the Ruby beginner, and will be of little use to someone new to programming. The book assumes a reasonable technical understanding of Ruby, and some experience in developing software with it.

The book is split into two parts, with eight chapters forming its core and three appendixes included as supplementary material.

This book provides a wealth of information on:

• Driving Code Through Tests - covers a number testing philosophies and techniques. Use mocks and stubs
• Designing Beautiful APIs with special focus on Ruby's secret powers: Flexible argument processing and code blocks
• Mastering the Dynamic Toolkit showing developers how to build flexible interfaces, implementing per-object behaviour, extending and modifying pre-existing code, and building classes and modules programmatically
• Text Processing and File Management focusing on regular expressions, working with files, the tempfile standard library, and text-processing strategies
• Functional Programming Techniques highlighting modular code organisation, memoization, infinite lists, and higher-order procedures
• Understand how and why things can go wrong explaining how to work with logger
• Reduce Cultural Barriers by leveraging Ruby's multilingual capabilities
• Skillful Project Maintenance

The book is open source, released under the Creative Commons NC-SA license.

2. Programming Ruby - The Pragmatic Programmer's Guide

Programming Ruby is a tutorial and reference for the Ruby programming language. Use Ruby, and you will write better code, be more productive, and make programming a more enjoyable experience.

Topics covered include:

• Classes, Objects and Variables
• Containers, Blocks and Iterators
• Standard Types
• More about Methods
• Expressions
• Exceptions, Catch and Throw
• Modules
• Basic Input and Output
• Threads and Processes
• When Trouble Strikes
• Ruby and its World, the Web, Tk, and Microsoft Windows
• Extending Ruby
• Reflection, ObjectSpace and Distributed Ruby
• Standard Library
• Object-Oriented Design Libraries
• Network and Web Libraries
• Embedded Documentation
• Interactive Ruby Shell

The first edition of this book is released under the Open Publication License, v1.0 or later. An updated Second Edition of this book, covering Ruby 1.8 and including descriptions of all the new libraries is available, but is not released under a freely distributable license.

3. Mr. Neighborly's Humble Little Ruby Book

Mr. Neighborly's Humble Little Ruby Book covers the Ruby language from the very basics of using puts to put phrases on the screen all the way to serving up your favorite web page from WEBrick or connecting to your favorite web service.

Written in a conversational narrative rather than like a dry reference book, Mr. Neighborly's Humble Little Ruby Book is an easy to read, easy to follow guide to all things Ruby.

Topics covered included methods, blocks and proc objects, conditionals, loops, exceptions, filesystem interacton, threads and processes, and networking.

4. Learn Ruby the Hard Way

Learn Ruby The Hard Way is a translation of the original "Learn Python The Hard Way" to teaching Ruby, with the translation done by Rob Sobers. "Learn Python The Hard Way" has taught hundreds of thousands worldwide how to code in Python, and this book uses the same method for Ruby.

The title says it is the hard way to learn to write code but it is actually not. It is the hard way only in that it is the way people used to teach things. In this book you will do something incredibly simple that all programmers actually do to learn a language.

This is a very beginner book for people who want to learn to code. If you can already code then look elsewhere. It is targeted for newbies to build up their skills before starting a more detailed book, such as Ruby Best Practices. 

Learn Ruby The Hard Way consists of:

• 52 Exercises which consist of typing code samples. This helps budding Ruby programmers to learn the names of the symbols, become familiar with typing them, and reading the language
• Exercises cover topics such as: Variables, printing, functions, boolean algebra, branches and functions, automated testing, and starting your own game