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This is a minimal tutorial to get started.

View the thing here.

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Here’s a clean, safe, and up-to-date way to install and update Ruby and RubyGems on macOS without touching the system Ruby. You’ll use Homebrew + rbenv, the most common modern setup (Ruby 3.4.7 is the latest release as of October 2025).

You need these for compiling Ruby.

xcode-select --install

Follow the pop-up instructions and wait for installation to complete.

Check:

brew -v

If not installed:

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

After install, make sure your shell sees brew:

Apple Silicon (M1/M2/M3):

echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> ~/.zprofile
eval "$(/opt/homebrew/bin/brew shellenv)"

Intel Macs:

echo 'eval "$(/usr/local/bin/brew shellenv)"' >> ~/.zprofile
eval "$(/usr/local/bin/brew shellenv)"

brew install rbenv ruby-build

These manage multiple Ruby versions completely separate from system Ruby.

Add rbenv to your shell startup:

echo 'eval "$(rbenv init - zsh)"' >> ~/.zshrc
source ~/.zshrc

Check rbenv:

rbenv -v

List available Ruby versions:

rbenv install -l

Install the latest stable (3.4.7):

rbenv install 3.4.7

Set it as the default for all shells:

rbenv global 3.4.7

Reload environment:

rbenv rehash

Confirm:

ruby -v
# → ruby 3.4.7 (2025-10-07)

Now that you’re using your own Ruby, safely update RubyGems:

gem update --system

Then update all installed gems:

gem update

Check where your Ruby and gem live (should not be /usr/bin):

which ruby
which gem

You should see something like:

/Users/<you>/.rbenv/shims/ruby
/Users/<you>/.rbenv/shims/gem

To update later:

brew upgrade rbenv ruby-build
rbenv install -l
rbenv install 3.4.x   # whatever the latest is
rbenv global 3.4.x
rbenv rehash

✅ Now you can safely run any gem install ... command — it’ll use your rbenv Ruby and not touch the macOS system Ruby.