安装:
curl -L https://get.rvm.io | bash -s stable --autolibs=enabled [--ruby] [--rails] [—trace]
$ curl -L get.rvm.io | bash -s stable
1. $ source ~/.bashrc
2. $ source ~/.bash_profile
3. rvm -v

卸载RVM:   rvm implode
$ cd ~ ; sudo rm -rf .rvm .rvmrc   /etc/rvmrc ;gem uninstall rvm