ubuntu下配置rails环境遇到的错误

1.Could not find gem 'sqlite3 (>= 0)' in any of the gem sources listed in you
r Gemfile

解决：sudo gem install sqlite3-ruby

2.ERROR:  While executing gem ... (Gem::FilePermissionError)
    You don't have write permissions into the /usr/local/lib/ruby/gems/1.9.1 director.y

解决：权限问题，前面加个sudo

3.rails 3遇到 Could not find a JavaScript runtime execjs错误（ubuntu）

解决：
sudo apt-get install python-software-properties  
sudo add-apt-repository ppa:chris-lea/node.js  
sudo apt-get update  
sudo apt-get install nodejs