Post OS X 10.10 Yosemite install Rails error - ruby-on-rails

Question

I did a clean install of Mac OS Yosemite, but now Rails won't work properly.
When I try to do rails s it tells me to do bundle install.
I get this message after trying to run bundle install:
Errno::EACCES: Permission denied - /Users/giowong/rails_project/doctible_pre_treatment/vendor/bundle/ruby/2.0.0/gems/bcrypt-3.1.7/.gitignore
I did
sudo gem update --system
and
bundle install
When I do this, I'm getting this nasty stuff:
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby -r ./siteconf20141107-39214-1ds3j4x.rb extconf.rb
checking for ruby/util.h... *** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details. You may
need configuration options.
Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:434:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:549:in `block in try_compile'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:502:in `with_werror'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:549:in `try_compile'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:1044:in `block in have_header'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:895:in `block in checking_for'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:340:in `block (2 levels) in postpone'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:310:in `open'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:340:in `block in postpone'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:310:in `open'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:336:in `postpone'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:894:in `checking_for'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:1043:in `have_header'
from extconf.rb:14:in `<main>'
extconf failed, exit code 1
Gem files will remain installed in /Users/giowong/rails_project/doctible_pre_treatment/vendor/bundle/ruby/2.0.0/gems/bcrypt-3.1.7 for inspection.
Results logged to /Users/giowong/rails_project/doctible_pre_treatment/vendor/bundle/ruby/2.0.0/extensions/universal-darwin-14/2.0.0/bcrypt-3.1.7/gem_make.out
An error occurred while installing bcrypt (3.1.7), and Bundler cannot continue.
Make sure that `gem install bcrypt -v '3.1.7'` succeeds before bundling.
I've tried installing using
\curl -sSL https://get.rvm.io | bash -s stable --rails
but no luck.

Answer 1

I don't recommend using the default Ruby provided with OS X, so install RVM instead. You will also need to install the Xcode command line tools:
xcode-select --install # click install, not Get Xcode
Then verify if gcc is installed:
gcc --version
And only then run:
\curl -sSL https://get.rvm.io | bash -s stable --rails