Ruby on rails 配置：错误：需要clang 3.0或更高版本，我已经有了它

我试图遵循，大概是针对雪豹10.6.8（我应该指出，

$rvm-v

返回

-bash:rvm:command not found

），但是当我运行

$curl-L时https://get.rvm.io |bash-s stable--auto dotfiles--autolibs=enable--rails

它以

Error running './configure --prefix=/Users/mac/.rvm/rubies/ruby-2.2.0 --with-opt-dir=/usr/local/opt/libyaml:/usr/local/opt/readline:/usr/local/opt/libksba:/usr/local/opt/openssl --disable-install-doc --enable-shared',
showing last 15 lines of /Users/mac/.rvm/log/1427567557_ruby-2.2.0/configure.log
[2015-03-28 15:33:08] ./configure
current path: /Users/mac/.rvm/src/ruby-2.2.0
PATH=/usr/local/opt/pkg-config/bin:/usr/local/opt/libtool/bin:/usr/local/opt/automake/bin:/usr/local/opt/autoconf/bin:/usr/local/bin:/usr/local/bin:/opt/local/bin:/opt/local/sbin:/Library/Frameworks/Python.framework/Versions/2.7/bin:/usr/bin/python:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/opt/X11/bin:/usr/local/git/bin:/usr/X11/bin:/Users/mac/.rvm/bin
command(5): ./configure --prefix=/Users/mac/.rvm/rubies/ruby-2.2.0 --with-opt-dir=/usr/local/opt/libyaml:/usr/local/opt/readline:/usr/local/opt/libksba:/usr/local/opt/openssl --disable-install-doc --enable-shared
config.guess already exists
config.sub already exists
checking build system type... i386-apple-darwin10.8.0
checking host system type... i386-apple-darwin10.8.0
checking target system type... i386-apple-darwin10.8.0
i686-apple-darwin10-gcc-4.2.1: error trying to exec 'cc1': execvp: No such file or directory
i686-apple-darwin10-gcc-4.2.1: error trying to exec 'cc1': execvp: No such file or directory
configure: error: clang version 3.0 or later is required
There has been an error while running configure. Halting the installation.

然后我跑了

$ which clang
/usr/bin/clang
$ clang -v
Apple clang version 3.0 (tags/Apple/clang-211.10.1) (based on LLVM 3.0svn)
Target: x86_64-apple-darwin10.8.0
Thread model: posix

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当我尝试安装RVM时，即使在重新启动后，也会收到相同的错误消息。目标是10.8.0这一事实显然有些奇怪，指南中甚至没有提到这一点，所以我真的需要实际的帮助。更新我的操作系统不是一个选项，所以请不要提出来。

我不知道10.6.8。我在10.7.5也有同样的问题。我能够从下载10.7版的XCode命令行实用程序：并安装clang版本4.2。