Installing Ruby

This course targets Ruby 3.4. Any newer version works too — the lessons avoid features that newer versions removed.

Windows

Download the RubyInstaller "with Devkit" from rubyinstaller.org and run it. At the end, let it run ridk install and choose the default option — that installs the build tools some gems need.

macOS

macOS includes an old system Ruby that you should not use or modify. Install a current version with Homebrew:

brew install ruby

Homebrew prints a line to add to your shell profile so its Ruby comes first on your PATH — follow it, then open a new terminal.

Linux

Your distribution's package (sudo apt install ruby-full on Debian/Ubuntu) is fine for learning, though it may be a version or two behind.

Version managers (optional)

Professional Ruby developers usually install Ruby through a version manager such as rbenv, chruby, or mise, which lets different projects use different Ruby versions side by side. You don't need one to follow this course, but you will meet them in real projects.

Check the installation

Open a new terminal and run:

ruby -v

You should see something like:

ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-linux]

The exact version, date, and platform will match what you installed. If the terminal says ruby: command not found (or "is not recognized" on Windows), close and reopen the terminal; if it still fails, Ruby's bin folder isn't on your PATH.