do this:
bash < <(curl -s https://rvm.beginrescueend.com/install/rvm)
add
[[ -s "$HOME/.rvm/scripts/rvm" ]] && . "$HOME/.rvm/scripts/rvm"

to your ~/.bashrc file (at the end) if it didn't do this for you already.
the rvm instructions tell you this.

open a new shell.
rvm install 1.9.2 (let it do its thing)
rvm 1.9.2
gem install bundler rails
rails new project_name_here

#enjoy your rails experience.
I know this is a lot of over head, but it gives you a lot of benefits.
name you can run multiple ruby interpreters, gems are a lot easier to deal =
with.
You aren't beholden to apple for ruby support.. it's what all the cool kids=
 use.

you'll want to learn about gemsets and etc, but this will get you
going in a good direction.

Andrew McElroy



On Sun, Sep 18, 2011 at 10:32 AM, andy p. <andy.prondak / gmail.com> wrote:
> Hey, this is my first time ever working with Ruby so this makes me a
> total n00b.
>
> Here is the error I received:
>
> bash-3.2$ sudo gem install rails
> Building native extensions. =A0This could take a while...
> ERROR: =A0Error installing rails:
> =A0ERROR: Failed to build gem native extension.
>
> /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
> extconf.rb
> mkmf.rb can't find header files for ruby at
> /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/ruby.=
h
>
>
> Gem files will remain installed in
> /Library/Ruby/Gems/1.8/gems/bcrypt-ruby-3.0.1 for inspection.
> Results logged to
> /Library/Ruby/Gems/1.8/gems/bcrypt-ruby-3.0.1/ext/mri/gem_make.out
>
>
> Here is the result logged:
>
> /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
> extconf.rb
> mkmf.rb can't find header files for ruby at
> /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/ruby.=
h
>
> Im assuming OSX Lion is missing something? Should I do an update?
>
> --
> Posted via http://www.ruby-forum.com/.
>
>