rails 之 DevKit

DevKit 是windows平台下编译和使用本地C/C++扩展包的工具。它就是用来模拟Linux平台下的make, gcc, sh来进行编译
今天在重做系统装rails时出现点小小问题
Please update your PATH to include build tools or download the DevKit
开始我不大注意，随便点击个下载安装，结果还是不正确，仔细一看才知道
NOTE: for the legacy RubyInstaller v1.8.6 use the DevKit-3.4.5 available at our archive downloads page. For RubyInstaller versions 1.8.7, 1.9.2, and 1.9.3 use the DevKit 4.5.2 from our main downloads page.
我装的ruby1.9.3，需要DevKit-3.4.5
然后从http://rubyinstaller.org/downloads/下载DevKit-3.4.5安装
如c:/devkit。(注意：目录不能有空格)
安装完后还需要几步才算是成功
1.>ruby dk.rb init 3
#生成config.yml这里会检查将要添加DevKit支持的Ruby列表只支持通过RubyInstaller安装的Ruby
2.>ruby dk.rb review  #检查要添加DevKit支持的Ruby列表是否有误可以略过
3.>ruby dk.rb install
4.[INFO] Updating convenience notice gem override for 'C:/Ruby192'
  [INFO] Installing 'C:/Ruby192/lib/ruby/site_ruby/devkit.rb'
5.#检查是否安装成功
>gem install rdiscount --platform=ruby
2 Fetching: rdiscount-1.6.8.gem (100%)
Temporarily enhancing PATH to include DevKit...
Building native extensions.  This could take a while...
Successfully installed rdiscount-1.6.8
1 gem installed
Installing ri documentation for rdiscount-1.6.8...
Installing RDoc documentation for rdiscount-1.6.8...
如果能安装rdiscount成功说明安装DevKit成功。 
详细资料
https://github.com/oneclick/rubyinstaller/wiki/development-kit