Rails4.2.5をWindows7にインストールする手順

# やりたいこと

* Rails4.2.5 を Windows7 にインストールする。

## 前提環境

* OS: Microsoft Windows 7 Professional 6.1.7601 Service Pack 1 (SP1) ビルド 7601 x64
* [Ruby: 2.2.4 (x64)](http://qiita.com/bu-son/items/abc9a100f5ab11063212) インストール済み
* [Devkit: mingw64-64-4.7.2-20130224-1432-sfx](http://qiita.com/bu-son/items/b274e4c273e30126526f) インストール済み
* [Windows7の.gemrc設定手順(プロキシ環境有)](http://qiita.com/bu-son/items/747661797fe1c1fd08c4) 設定済み

## インストールするソフトウェア

* Rails: 4.2.5

## 手順

### インストール

コマンドプロンプト(cmd)で下記のコマンドを実行します。

```bat:cmd.exe
gem install rails --version="4.2.5"　:: <= 実行するコマンド
Fetching: i18n-0.7.0.gem (100%)
Successfully installed i18n-0.7.0
Fetching: thread_safe-0.3.5.gem (100%)
Successfully installed thread_safe-0.3.5
Fetching: tzinfo-1.2.2.gem (100%)
Successfully installed tzinfo-1.2.2
Fetching: activesupport-4.2.5.gem (100%)
Successfully installed activesupport-4.2.5
Fetching: builder-3.2.2.gem (100%)
Successfully installed builder-3.2.2
Fetching: erubis-2.7.0.gem (100%)
Successfully installed erubis-2.7.0
Fetching: mini_portile2-2.0.0.gem (100%)
Successfully installed mini_portile2-2.0.0
Fetching: nokogiri-1.6.7.2-x64-mingw32.gem (100%)
Nokogiri is built with the packaged libraries: libxml2-2.9.2, libxslt-1.1.28, zlib-1.2.8, libiconv-1.14.
Successfully installed nokogiri-1.6.7.2-x64-mingw32
Fetching: rails-deprecated_sanitizer-1.0.3.gem (100%)
Successfully installed rails-deprecated_sanitizer-1.0.3
Fetching: rails-dom-testing-1.0.7.gem (100%)
Successfully installed rails-dom-testing-1.0.7
Fetching: loofah-2.0.3.gem (100%)
Successfully installed loofah-2.0.3
Fetching: rails-html-sanitizer-1.0.3.gem (100%)
Successfully installed rails-html-sanitizer-1.0.3
Fetching: actionview-4.2.5.gem (100%)
Successfully installed actionview-4.2.5
Fetching: rack-1.6.4.gem (100%)
Successfully installed rack-1.6.4
Fetching: rack-test-0.6.3.gem (100%)
Successfully installed rack-test-0.6.3
Fetching: actionpack-4.2.5.gem (100%)
Successfully installed actionpack-4.2.5
Fetching: globalid-0.3.6.gem (100%)
Successfully installed globalid-0.3.6
Fetching: activejob-4.2.5.gem (100%)
Successfully installed activejob-4.2.5
Fetching: mime-types-2.99.gem (100%)
Successfully installed mime-types-2.99
Fetching: mail-2.6.3.gem (100%)
Successfully installed mail-2.6.3
Fetching: actionmailer-4.2.5.gem (100%)
Successfully installed actionmailer-4.2.5
Fetching: activemodel-4.2.5.gem (100%)
Successfully installed activemodel-4.2.5
Fetching: arel-6.0.3.gem (100%)
Successfully installed arel-6.0.3
Fetching: activerecord-4.2.5.gem (100%)
Successfully installed activerecord-4.2.5
Fetching: bundler-1.11.2.gem (100%)
Successfully installed bundler-1.11.2
Fetching: thor-0.19.1.gem (100%)
Successfully installed thor-0.19.1
Fetching: railties-4.2.5.gem (100%)
Successfully installed railties-4.2.5
Fetching: concurrent-ruby-1.0.0.gem (100%)
Successfully installed concurrent-ruby-1.0.0
Fetching: sprockets-3.5.2.gem (100%)
Successfully installed sprockets-3.5.2
Fetching: sprockets-rails-3.0.1.gem (100%)
Successfully installed sprockets-rails-3.0.1
Fetching: rails-4.2.5.gem (100%)
Successfully installed rails-4.2.5
31 gems installed
```

### インストール後の確認

```bat:cmd.exe
rails -v :: <= 実行するコマンド
Rails 4.2.5
```

### 完了