Install ror in ubuntu

1. Regardless of 3721, run: sudo apt-get update -- upgrade first.
2. Then use rvm for Installation
3. if the rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/yaml appears. rb: 56: in '<top (required)>': If this error occurs, run: sudo apt-get install libyaml-0-2 libyaml-dev -- install libyaml
4. if Permission denied... is not displayed, try sudo... For example: sudo gem install rails -- include-dependencies
5. In short, Baidu and google are all about any errors. They are good at discovering error prompts, and then think about where the possible problems are and solve them. Author dgz888