错误如下，在线等，谢谢
rvm install ruby-2.2
Searching for binary rubies, this might take some time.
No binary rubies available for: ubuntu/14.04/x86_64/ruby-2.2.1.
Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
Checking requirements for ubuntu.
Installing requirements for ubuntu.
mkdir: 无法创建目录"/usr/local/rvm/log/1443528316_ruby-2.2.1": 权限不够
tee: /usr/local/rvm/log/1443528316_ruby-2.2.1/update_system.log: 没有那个文件或目录
Updating systemfangshuxian password required for 'apt-get --quiet --yes update':
............
Error running 'requirements_debian_update_system ruby-2.2.1',
showing last 15 lines of /usr/local/rvm/log/1443528316_ruby-2.2.1/update_system.log
tail: 无法打开"/usr/local/rvm/log/1443528316_ruby-2.2.1/update_system.log" 读取数据: 没有那个文件或目录
Requirements installation failed with status: 1.
mkdir: 无法创建目录"/usr/local/rvm/log/1443528316_ruby-2.2.1": 权限不够
权限的问题，先sudo提权。