Scripts to set up Ruby 1.9.3 on a DreamHost shared hosting account via rbenv and ruby-build, and run a Rack app with it via FastCGI.

.htaccess

<IfModule mod_fastcgi.c>
AddHandler fastcgi-script .fcgi
</IfModule>
<IfModule mod_fcgid.c>
AddHandler fcgid-script .fcgi
</IfModule>

Options +FollowSymLinks +ExecCGI 

RewriteEngine On 

RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)$ dispatch.fcgi/$1 [QSA,L]

dispatch.fcgi

#!/bin/bash
this_dir=`dirname $0`
unset GEM_HOME
unset GEM_PATH
export PATH=~/.rbenv/bin:"$PATH"
eval "$(~/.rbenv/bin/rbenv init -)"
err_log_file="${this_dir}/log/dispatch_err.log"
exec ~/.rbenv/shims/ruby "${this_dir}/dispatch_fcgi.rb" "$@" 2>>"${err_log_file}"

dispatch_fcgi.rb

require 'rubygems'
require 'bundler'
Bundler.setup(:default, :fcgi)
require 'rack'

class Rack::PathInfoRewriter
  def initialize(app)
    @app = app
  end

  def call(env)
    env['SCRIPT_NAME'] = ''  # Don't delete it--Rack::URLMap assumes it is not nil
    pathInfo, query = env['REQUEST_URI'].split('?', 2)
    env['PATH_INFO'] = pathInfo
    env['QUERY_STRING'] = query
    @app.call(env)
  end
end

app, options = Rack::Builder.parse_file('config.ru')
wrappedApp = Rack::Builder.new do
  use Rack::ShowExceptions
  use Rack::PathInfoRewriter
  run app
end

Rack::Handler::FastCGI.run wrappedApp

dreamhost_rbenv_setup.sh

# Initial setup for Ruby 1.9.3 on DreamHost shared hosting.
# We assume you're already in your project's root directory, which should
# also be the directory configured as "web directory" for your domain
# in the DreamHost panel.


# Install rbenv and ruby-build
git clone git://github.com/sstephenson/rbenv.git ~/.rbenv
git clone git://github.com/sstephenson/ruby-build.git ~/.rbenv/plugins/ruby-build

# Create temporary directory--DreamHost does not allow files in /tmp to be 
# executed, which makes the default not work
mkdir ~/.rbenv/BUILD_TEMP

# DreamHost will set your GEM_HOME and GEM_PATH for you, but this conflicts
# with rbenv, so we unset them here.  You'll want to do this in your .bashrc
# on the dreamhost account.
unset GEM_HOME
unset GEM_PATH

# Add rbenv to PATH and let it set itself up.
# You probably want these two lines in your .bashrc as well:
export PATH=~/.rbenv/bin:"$PATH"
eval "$(~/.rbenv/bin/rbenv init -)"

# Decide which version of Ruby we're going to install and use.
NEW_RUBY_VERSION=1.9.3-p327

# Using that as the temp space, build and install ruby 1.9.3.
# The MAKE_OPTS=-j2 part is to limit make to 2 simultaneous jobs,
# so that DreamHost won't kill the build of ruby.
TMPDIR=~/.rbenv/BUILD_TEMP MAKE_OPTS=-j2 rbenv install $NEW_RUBY_VERSION

# Now everything is set up properly, you should be able to set your
# directory to use the new ruby:
rbenv local $NEW_RUBY_VERSION

# Bundler isn't included with ruby, so install it first:
gem install bundler

# Make sure rbenv picks up the newly installed bundler:
rbenv rehash

# Then use it to install the rest of your gems:
bundle install

# Create the "log" dir in for the file containing the stderr of your dispatch.fcgi script:
mkdir -p log