log of installing rbenv and ruby-build

1_install_rbenv

$ brew install rbenv
==> Downloading https://github.com/sstephenson/rbenv/archive/v0.4.0.tar.gz
######################################################################## 100.0%
==> Caveats
To use Homebrew's directories rather than ~/.rbenv add to your profile:
  export RBENV_ROOT=/usr/local/var/rbenv

To enable shims and autocompletion add to your profile:
  if which rbenv > /dev/null; then eval "$(rbenv init -)"; fi
==> Summary
🍺  /usr/local/Cellar/rbenv/0.4.0: 31 files, 152K, built in 4 seconds

2_install_ruby-build

$ brew install ruby-build
==> Installing ruby-build dependency: autoconf
==> Downloading http://ftpmirror.gnu.org/autoconf/autoconf-2.69.tar.gz
######################################################################## 100.0%
==> ./configure --prefix=/usr/local/Cellar/autoconf/2.69
==> make install
🍺  /usr/local/Cellar/autoconf/2.69: 69 files, 2.0M, built in 7 seconds
==> Installing ruby-build dependency: pkg-config
==> Downloading https://downloads.sf.net/project/machomebrew/Bottles/pkg-config-0.28.mountain_lion.bottle.tar.gz
######################################################################## 100.0%
==> Pouring pkg-config-0.28.mountain_lion.bottle.tar.gz
🍺  /usr/local/Cellar/pkg-config/0.28: 10 files, 636K
==> Installing ruby-build
==> Downloading https://github.com/sstephenson/ruby-build/archive/v20130227.tar.gz
######################################################################## 100.0%
==> ./install.sh
🍺  /usr/local/Cellar/ruby-build/20130227: 72 files, 320K, built in 4 seconds

3_install_ruby_but_error

$ CONFIGURE_OPTS="--with-readline-dir=/usr/local" rbenv install 1.9.2-p320

ERROR: This package must be compiled with GCC, but ruby-build couldn't
find a suitable `gcc` executable on your system. Please install GCC
and try again.

DETAILS: Apple no longer includes the official GCC compiler with Xcode
as of version 4.2. Instead, the `gcc` executable is a symlink to
`llvm-gcc`, a modified version of GCC which outputs LLVM bytecode.

For most programs the `llvm-gcc` compiler works fine. However,
versions of Ruby older than 1.9.3-p125 are incompatible with
`llvm-gcc`. To build older versions of Ruby you must have the official
GCC compiler installed on your system.

TO FIX THE PROBLEM: Install the official GCC compiler using these
packages: https://github.com/kennethreitz/osx-gcc-installer/downloads

You will need to install the official GCC compiler to build older
versions of Ruby even if you have installed Apple's Command Line Tools
for Xcode package. The Command Line Tools for Xcode package only
includes `llvm-gcc`.

BUILD FAILED

4_instal_ruby

$ CONFIGURE_OPTS="--with-readline-dir=/usr/local" rbenv install 1.9.2-p320
Downloading http://pyyaml.org/download/libyaml/yaml-0.1.4.tar.gz...
Installing yaml-0.1.4...
Installed yaml-0.1.4 to /Users/matsuda/.rbenv/versions/1.9.2-p320
Downloading http://ftp.ruby-lang.org/pub/ruby/1.9/ruby-1.9.2-p320.tar.gz...
Installing ruby-1.9.2-p320...
Installed ruby-1.9.2-p320 to /Users/matsuda/.rbenv/versions/1.9.2-p320
Downloading http://production.cf.rubygems.org/rubygems/rubygems-1.8.23.tgz...
Installing rubygems-1.8.23...
Installed rubygems-1.8.23 to /Users/matsuda/.rbenv/versions/1.9.2-p320