Ruby is an easy language to learn, but it's often necessary to look up something we've forgotten. A combination of Google plus any Ruby books we have on our shelves can help, but sometimes it's handy to refer to a simpler set of notes - such as a 'cheat sheet.' This post attempts to cover the most interesting ones.
On with the Ruby cheat sheets:
Ruby Methods Cheat Sheet
'Essential Ruby' RefCard (PDF)
Essential Ruby is a combination of a cheat sheet and a tutorial. It's six pages long, but features a mini Ruby introduction and tutorial, as well as the myriad of tables you'd expect from a cheat sheet. It's like a whole Ruby beginner's reference and tutorial in a single PDF. The only 'catch' is that you need to be a user of DZone (the 'Digg for Developers') or JavaLobby to get it, but there's a very simple signup form you can fill in if you're not.
Ruby Cheatsheet (PDF and PNG)
This cheat sheet (homepage) covers types, exceptions, expressions, variable types, operators and precedence, constants, regular expressions, predefined / special variables, arguments accepted by the Ruby interpreter, reserved words, and a large collection of Object, String, Kernel, Array, Hash, Test::Unit, File, Dir and DateTime methods. Extremely suitable for printing and/or wall chart use.
Ruby QuickRef (HTML)
I often use this one myself! A ridiculously comprehensive 'cheat sheet' created by Ryan Davis covering syntax rules, reserved words, regular expression terminology, class and method definitions, predefined variables and constants, control and logic expressions and formations, exceptions, the standard library, and a whole ton of useful stuff.
Ruby Reference (PDF)
More of an extremely brief reference than a truly comprehensive cheat sheet, but still useful, especially for beginners. 5 pages long, so not suitable for printing (Also available to view on the Web at Scribd.)
Cheat: Ruby Cheat Sheets on your Terminal! (Application)
Not a cheat sheet, but an application (gem install cheat) that provides cheat sheet type reference material on your terminal (from 228 source cheat sheets!) Developed by the great guys over at Err Free.
A Beginner's Notes (HTML)
A set of notes made by a beginning Ruby developer as he works his way through a Ruby manual.
Ruby Command Line Parameters Cheat Sheet (HTML)
A simplified list of the command line options offered by the Ruby interpreter.
Strftime Parameters (HTML)
Ruby Cheatsheet Pdf
A handy guide to the formatting parameters accepted by strftime. I commonly have to look these up myself!