2. Setting Up Your Dev Environment

Before you can start writing awesome Ruby code on your computer, you’ll need to do some setup on it. You can’t code Ruby without the MRI – the Ruby interpreter, remember? – and a code editor. A code editor is just a fancy word for text editor – it makes you sound cooler!

Branching Lessons – Which One Is For You?

The next three lessons are broken down by operating system: OS X, Windows, and Linux. Feel free to skip to the lesson for your operating system. And if you have any problems with installations, head over to the Forums and ask for help!

The Command-Line Interface

You’ve probably heard some of the following terms before: command-line interface, command prompt, DOS window, terminal, console, CLI, etc.

These are all terms for the same thing, so don’t feel confused if you hear someone talk about the terminal and the console at the same time. To make it easy on you, we’ll always use the term CLI when referring to a command-line interface.

What is a CLI? Think of your operating system: there are icons you click on with your mouse or tap with your fingers to open programs, menus you open and scroll through for options, windows you can resize and move around, and other nifty graphical controls. This is called a graphical user interface because it uses visual representations to help you do your work.

Before graphical user interfaces – or just GUI for short – people communicated with their computers through typing in text commands. There were no fancy icons or graphics to help you out. This is called a command-line interface – CLI.

Even though CLI’s are a remnant of the past, they are still widely used today by programmers and system administrators to issue commands that don’t matter to the users but are important to the computer.

CLI’s come in various shapes and sizes. Depending on the system you use, your CLI may look very different from others:

We’ll be using the CLI a lot during this course. In fact, we’ll need it to set up our dev environment right now!

We know you’re a smart person – you can download and install software on your computer without us holding your hand. But the CLI isn’t something that most computer users are familiar with, so we’re going to take a look at how to work with some CLI commands.


This was a short lesson, but now you know what a CLI is and what they’re used for!

You can skip to the next lesson that covers how to use the CLI and install Ruby for your operating system. However, we do recommend that you at least glance through the lessons for the other operating systems too – it will give you a feel for how things are done across other platforms.

Important Words

  • Command-line interface (CLI)
  • Command prompt
  • Console
  • Terminal
  • Graphical User Interface (GUI)


We’ll go easy on you this time: all you have to do is hop into the Forums and post what platform you use – Windows, OS X, or Linux – and why. The more we know about you, the better our lessons will be!

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