MacのRubyのバージョンを 2.1.1 に上げてみた ref: http://qiita.com/masamitsu-konya/items/3eb633b035c89d1751d4

file0.txt

brew update
brew upgrade ruby-build

file1.txt

rbenv install -l

...
2.0.0-rc1
2.0.0-rc2
2.1.0-dev
2.1.0-preview1
jruby-1.5.6
...

file2.txt

cd ~/.rbenv/plugin/ruby-build
git pull origin master

file3.txt

rbenv install -l

...
2.1.0-rc1
2.1.1
2.2.0-dev
...

file4.txt

rbenv install 2.1.1

file5.txt

rbenv versions

  system
  1.9.3-p392
  1.9.3-p448
* 2.0.0-p247 (set by /Users/masamitsu/.rbenv/version)
  2.1.1

file6.txt

rbenv global 2.1.1

rbenv versions

  system
  1.9.3-p392
  1.9.3-p448
  2.0.0-p247
* 2.1.1 (set by /Users/masamitsu/.rbenv/version)

file7.txt

sudo rbenv uninstall 1.9.3-p392
sudo rbenv uninstall 1.9.3-p448