Packages (RubyGems & Bundler) in Ruby

Manage Ruby dependencies using RubyGems and Bundler, and understand Gemfile and Gemfile.lock.

What is RubyGems?

RubyGems is Ruby's built-in package manager. A "gem" is a packaged Ruby library or tool. The gem command lets you install, update, and remove gems from your system.

1. Installing a Gem

Install a package from RubyGems.org.

2. Listing Installed Gems

See what's installed.

3. Uninstalling a Gem

Remove an installed gem.

4. Using a Gem in Code

require loads the gem.

Bundler

Bundler manages gem dependencies for a project. It ensures every developer and deployment uses the same gem versions. Bundler reads a Gemfile to know what gems are needed.

1. Installing Bundler

Bundler is itself a gem.

2. The Gemfile

Declare project dependencies.

3. bundle install

Install all gems in the Gemfile.

4. Gemfile.lock

Pin exact versions for reproducible builds.

Common Bundler Commands

These are the most common Bundler commands you will use in any Ruby project.

1. bundle exec

Run a command using the project's gems.

2. bundle add

Add a gem and install it.

3. bundle update

Update gems to newer allowed versions.

4. bundle outdated

See which gems have newer versions available.

Loading Gems in Your App

In a script, use require explicitly. In a Bundler-managed app (like Sinatra or Rails), Bundler.require loads all Gemfile gems automatically.

1. Explicit require

Load one gem manually.

2. Bundler.require — Load All Gems

Auto-load all Gemfile gems.