<DEVKIT_INSTALL_DIR>。
> cd <DEVKIT_INSTALL_DIR>
> ruby dk.rb init
#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
#如果这里列出的Ruby与你的要求不符，可以手动修改
> ruby dk.rb review #检查要添加DevKit支持的Ruby列表是否有误，可以略过
> ruby dk.rb install
[INFO] Updating convenience notice gem override for 'C:/Ruby192'
[INFO] Installing 'C:/Ruby192/lib/ruby/site_ruby/devkit.rb'
检查是否安装成功
> gem install rdiscount --platform=ruby
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...
如果能安装成功，就说明安装成功。