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3. Installing Ruby

Installing Ruby on Your System

Before we can use Rails, we need to install Ruby. The best way to manage Ruby versions is using a version manager like rbenv or rvm.

Installing on macOS

Step 1: Install Homebrew (if not already installed)

Homebrew is the package manager for macOS. Open Terminal and run:

bash
1/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

Step 2: Install rbenv

rbenv lets you easily switch between multiple Ruby versions:

bash
1# Install rbenv and ruby-build
2brew install rbenv ruby-build
3
4# Add rbenv to your shell
5echo 'eval "$(rbenv init - zsh)"' >> ~/.zshrc
6
7# Reload your shell
8source ~/.zshrc

Step 3: Install Ruby

Now install the latest Ruby version:

bash
1# List available Ruby versions
2rbenv install -l
3
4# Install Ruby 3.3.0 (or latest stable)
5rbenv install 3.3.0
6
7# Set it as the global default
8rbenv global 3.3.0
9
10# Verify installation
11ruby -v
12# Output: ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [arm64-darwin23]

Installing on Ubuntu/Debian Linux

Step 1: Install dependencies

bash
1sudo apt update
2sudo apt install -y git curl libssl-dev libreadline-dev zlib1g-dev \
3  autoconf bison build-essential libyaml-dev libreadline-dev \
4  libncurses5-dev libffi-dev libgdbm-dev

Step 2: Install rbenv

bash
1# Clone rbenv
2git clone https://github.com/rbenv/rbenv.git ~/.rbenv
3
4# Add to PATH
5echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bashrc
6echo 'eval "$(rbenv init - bash)"' >> ~/.bashrc
7source ~/.bashrc
8
9# Install ruby-build plugin
10git clone https://github.com/rbenv/ruby-build.git ~/.rbenv/plugins/ruby-build

Step 3: Install Ruby

bash
1rbenv install 3.3.0
2rbenv global 3.3.0
3ruby -v

Installing on Windows

For Windows, we recommend using WSL2 (Windows Subsystem for Linux):

Step 1: Enable WSL2

Open PowerShell as Administrator:

powershell
1wsl --install

Step 2: Install Ubuntu from Microsoft Store

After restarting, install Ubuntu from the Microsoft Store, then follow the Linux instructions above.

Verifying Your Installation

Run these commands to verify everything is working:

bash
1# Check Ruby version
2ruby -v
3
4# Check gem (Ruby's package manager)
5gem -v
6
7# Check bundler (manages gem dependencies)
8gem install bundler
9bundler -v

Common Issues and Fixes

Permission errors with gems

Never use sudo to install gems. If you get permission errors:

bash
1# Check that rbenv is properly configured
2which ruby
3# Should show: /Users/yourname/.rbenv/shims/ruby
4
5# If not, reinitialize rbenv
6rbenv init
7source ~/.zshrc  # or ~/.bashrc

OpenSSL errors

If you see SSL certificate errors:

bash
1# macOS
2brew install openssl
3RUBY_CONFIGURE_OPTS="--with-openssl-dir=$(brew --prefix openssl)" rbenv install 3.3.0

You're now ready to install Rails and create your first application!