Install Rails 3.2.8 for Mac OS X Mountain Lion (10.8.2)

00_prepare

1. Install Xcode 4.5.1 from AppStore.
1. Install Command Line Tools via Xcode preferences.

01_install_homebrew

$ ruby -e "$(curl -fsSkL raw.github.com/mxcl/homebrew/go)"
$ brew doctor
Your system is raring to brew.

02_install_rbenv

$ brew install rbenv

03_add_to_bash_profile

if which rbenv > /dev/null; then eval "$(rbenv init -)"; fi

04_reload_bash_profile

$ source ~/.bash_profile

05_install_ruby_build

$ brew install ruby-build
$ rbenv install -l
Available versions:
  1.8.6-p383
  1.8.6-p420
  1.8.7-p249
  1.8.7-p302
...
  1.9.3-p0
  1.9.3-p125
  1.9.3-p194
  1.9.3-preview1
…

06_install_ruby

$ rbenv install 1.9.3-p194
$ rbenv versions
  1.9.3p194
$ rbenv global 1.9.3-p194
$ rbenv rehash
$ ruby -v
ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-darwin12.2.0]
$ which ruby
/Users/inoue/.rbenv/shims/ruby

07_install_rails

$ gem install rails
$ source ~/.bash_profile
$ rails -v
Rails 3.2.8

08_create_new_app

$ rails new helloworld
$ cd helloworld/
$ rails s
=> Booting WEBrick
=> Rails 3.2.8 application starting in development on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
[2012-10-14 12:51:43] INFO  WEBrick 1.3.1
[2012-10-14 12:51:43] INFO  ruby 1.9.3 (2012-04-20) [x86_64-darwin12.2.0]
[2012-10-14 12:51:43] INFO  WEBrick::HTTPServer#start: pid=28949 port=3000

It didn't happen for me, still 1.8.7. Thank you though.

@Soulkey, executing:

eval "$(rbenv init -)"

after this step:

rbenv global 1.9.3-p194

is working for me, see here for details https://github.com/sstephenson/rbenv#homebrew-on-mac-os-x

add it to bash profile to make it persist

$ echo 'eval "$(rbenv init -)"' >> $HOME/.bash_profile
$ source ~/.bash_profile