步骤1 － 安装 RVM
RVM 是干什么的这里就不解释了，后面你将会慢慢搞明白。
$ curl -L https://get.rvm.io | bash -s stable
期间可能会问你sudo管理员密码，这里可能需要等待一段时间后就可以成功安装好 RVM。
案例信息如下：
lihuifengdeMacBook-Pro:~ lihuifeng$ curl -L https://get.rvm.io | bash -s stable
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 184 100 184 0 0 8 0 0:00:23 0:00:21 0:00:02 8
100 22817 100 22817 0 0 523 0 0:00:43 0:00:43 --:--:-- 1056
Downloading https://github.com/wayneeseguin/rvm/archive/1.26.10.tar.gz
Downloading https://github.com/wayneeseguin/rvm/releases/download/1.26.10/1.26.10.tar.gz.asc
Found PGP signature at: 'https://github.com/wayneeseguin/rvm/releases/download/1.26.10/1.26.10.tar.gz.asc',
but no GPG software exists to validate it, skipping.
Upgrading the RVM installation in /Users/lihuifeng/.rvm/
RVM PATH line found in /Users/lihuifeng/.profile /Users/lihuifeng/.bashrc /Users/lihuifeng/.zshrc.
RVM sourcing line found in /Users/lihuifeng/.bash_profile /Users/lihuifeng/.zlogin.
Upgrade of RVM in /Users/lihuifeng/.rvm/ is complete.
# lihuifeng,
#
# Thank you for using RVM!
# We sincerely hope that RVM helps to make your life easier and more enjoyable!!!
#
# ~Wayne, Michal & team.
In case of problems: http://rvm.io/help and https://twitter.com/rvm_io
Upgrade Notes:
* No new notes to display.
－－这里就表示已经成功安装了－－
然后，载入 RVM 环境
$ source ~/.rvm/scripts/rvm
检查一下是否安装正确 ：输入命令 rvm -v ，如果正确会列出RVM版本 如下所示：
$ rvm -v
A RVM version 1.26.10 (latest) is installed yet 1.25.28 (stable) is loaded.
Please do one of the following:
* 'rvm reload'
* open a new shell
* 'echo rvm_auto_reload_flag=1 >> ~/.rvmrc' # for auto reload with msg.
* 'echo rvm_auto_reload_flag=2 >> ~/.rvmrc' # for silent auto reload.
步骤2 － 用 RVM 安装 Ruby 环境
输入命令 $ rvm install 2.0.0
$ rvm install 2.0.0
同样继续等待漫长的下载，编译过程，完成以后就安装好了。
A RVM version 1.26.10 (latest) is installed yet 1.25.28 (stable) is loaded.
Please do one of the following:
* 'rvm reload'
* open a new shell
* 'echo rvm_auto_reload_flag=1 >> ~/.rvmrc' # for auto reload with msg.
* 'echo rvm_auto_reload_flag=2 >> ~/.rvmrc' # for silent auto reload.
步骤3 － 设置 Ruby 版本
RVM 装好以后，需要执行下面的命令将指定版本的 Ruby 设置为系统默认版本
测试是否正确
lihuifengdeMacBook-Pro:~ lihuifeng$ ruby -v
ruby 2.0.0p481 (2014-05-08 revision 45883) [x86_64-darwin13.1.0]
lihuifengdeMacBook-Pro:~ lihuifeng$ gem -v
2.2.2
这有可能是因为Ruby的默认源使用的是cocoapods.org，国内访问这个网址有时候会有问题，网上的一种解决方案是将远替换成淘宝的，替换方式如下：
$gem source -r https://rubygems.org/
$ gem source -a https://ruby.taobao.org
lihuifengdeMacBook-Pro:~ lihuifeng$ gem source -r https://rubygems.org/
https://rubygems.org/ removed from sources
lihuifengdeMacBook-Pro:~ lihuifeng$ gem source -a https://ruby.taobao.org
https://ruby.taobao.org added to sources
要想验证是否替换成功了，可以执行：
$ gem sources -l
正常的输出结果：
这里就表示已经把Ruby环境成功的安装到了Mac 上了。