1.安装ruby
2.安装rails
sudo gem install rails -V
增加-V参数可看到安装过程
ERROR: Error installing rails:
ERROR: Failed to build gem native extension.
/usr/bin/ruby1.9.1 extconf.rb
/usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load such file -- mkmf
报错，安装ruby19.1-dev
再次安装rails