状況

Ruby on Rails チュートリアルの「1.2.4 Bundler」を見ていた
他にも、生まれて初めてプログラミングをする文系人間のためのチュートリアルも見ていた

起こったこと

Gemfileを設定した後、bundle update と bundle install を使用してgemをインストールしようとした
そうしたら、以下のようなエラーが表示された
Could not find gem 'turbolinks1.1.1 (>= 0) ruby' in the gems available on this machine.

対処方法

コンマ(,) を忘れずにつける
正しくは gem 'turbolinks', '1.1.1' だったが、 gem 'turbolinks' '1.1.1' にしていた

FYI

参考した記事

gemのインストールからデフォルトのRailsページを表示するまで

変更前のファイル

Gemfile

source 'https://rubygems.org'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.0.5'

# Use sqlite3 as the database for Active Record
gem 'sqlite3'

# Use SCSS for stylesheets
gem 'sass-rails', '~> 4.0.2'

# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'

# Use CoffeeScript for .js.coffee assets and views
gem 'coffee-rails', '~> 4.0.0'

# See https://github.com/sstephenson/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby

# Use jquery as the JavaScript library
gem 'jquery-rails'

# Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks
gem 'turbolinks'

# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 1.2'

group :doc do
  # bundle exec rake doc:rails generates the API under doc/api.
  gem 'sdoc', require: false
end

# Use ActiveModel has_secure_password
# gem 'bcrypt', '~> 3.1.7'

# Use unicorn as the app server
# gem 'unicorn'

# Use Capistrano for deployment
# gem 'capistrano', group: :development

# Use debugger
# gem 'debugger', group: [:development, :test]

正しく動作したファイル

Gemfile

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
ruby '2.0.0'
gem 'rails', '4.0.5'
# Use sqlite3 as the database for Active Record
gem 'sqlite3', '1.3.8'
# Use SCSS for stylesheets
gem 'sass-rails', '4.0.2'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '2.1.1'
# Use CoffeeScript for .coffee assets and views
gem 'coffee-rails', '4.0.1'
# See https://github.com/sstephenson/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby

# Use jquery as the JavaScript library
gem 'jquery-rails', '3.0.4'
# Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks
gem 'turbolinks', '1.1.1'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '1.0.2'
# bundle exec rake doc:rails generates the API under doc/api.
gem 'sdoc', '0.3.20', require: false