在我的RailsTutorial（在我的笔记本电脑设置中）使用此命令时：
rvm use 2.0.0@railstutorial_rails_4_0 --create --default
我收到以下错误：
laptop:rubygems-1.8.25 USER_NAME$ rvm use 2.0.0@railstutorial_rails_4_0 --create --default
Using /Users/USER_NAME/.rvm/gems/ruby-2.0.0-p451 with gemset railstutorial_rails_4_0
/Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/yaml.rb:4:in `<top (required)>':
It seems your ruby installation is missing psych (for YAML output).
To eliminate this warning, please install libyaml and reinstall your ruby.
/Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require': dlopen(/Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/x86_64-darwin13.1.0/psych.bundle, 9): Library not loaded: /usr/local/lib/libyaml-0.2.dylib (LoadError)
Referenced from: /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/x86_64-darwin13.1.0/psych.bundle
Reason: image not found - /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/x86_64-darwin13.1.0/psych.bundle
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/psych.rb:1:in `<top (required)>'
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/yaml.rb:5:in `<top (required)>'
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/rubygems.rb:600:in `load_yaml'
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/rubygems/config_file.rb:314:in `load_file'
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/rubygems/config_file.rb:191:in `initialize'
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/rubygems/gem_runner.rb:66:in `new'
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/rubygems/gem_runner.rb:66:in `do_configuration'
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/lib/ruby/2.0.0/rubygems/gem_runner.rb:46:in `run'
from /Users/USER_NAME/.rvm/rubies/ruby-2.0.0-p451/bin/gem:21:in `<main>'
我重新安装了libyaml，并重新安装了ruby，这一切都返回了这些错误。无论我做什么，我总是最终回到这个错误列表。