Languages

Ruby Cheat Sheet

Print-ready cheat sheet for Ruby, organized for fast lookup, study, and desk-side use

Source: Ruby Documentation (ruby-lang.org)
License: MIT
Updated: 2026-03-27

Sample

What's in this cheat sheet

Basics
Strings
Arrays & Hashes
Control Flow
Methods
Classes
Modules
Blocks & Iterators
Regex
File I/O

Hello World

puts "Hello, World!"
print "no newline"
p [1, 2, 3]   # inspect output: [1, 2, 3]

Run Ruby

ruby script.rb          # run a file
ruby -e 'puts "hi"'    # run inline
irb                     # interactive REPL

Variables

`name`	Local variable
`@name`	Instance variable
`@@count`	Class variable
`$debug`	Global variable
`MAX_SIZE`	Constant (uppercase by convention)

Download the full cheat sheet for all sections, formatted for print

Download PDF

Downloads

Choose the treatment that matches how you read

Recommended

Standard

B&W, ink-efficient. The default for laser printers and photocopies

Best for Printouts and desk-side reference

PDF 2 pages Letter landscape

Download PDF
Color

Warm color accents for on-screen reading or color printers

Best for Screen reading or color printers

PDF 2 pages Letter landscape

Download PDF
Reference Card

Maximum density, 4-column layout. Everything on one page

Best for Fast scanning and minimum paper use

PDF 1 page Letter landscape

Download PDF