Install rails on Mac OS X

I try to install Rails on Mac OS X. I already installed ruby.

$ ruby -v
ruby 2.0.0p247 (2013-06-27 revision 41674) [x86_64-darwin11.4.2]

I check whether Rails is installed:

$ rails -v 
Rails is not currently installed on this system. To get the latest version, simply type:

    $ sudo gem install rails

You can then rerun your "rails" command.

Then I run:

$ sudo gem install rails
Password:
Successfully installed rails-4.0.0
Parsing documentation for rails-4.0.0
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/belongs_to.png, skipping
unable to convert "\xF4" from ASCII-8BIT to UTF-8 for guides/assets/images/book_icon.gif, skipping
unable to convert "\x91" from ASCII-8BIT to UTF-8 for guides/assets/images/bullet.gif, skipping
unable to convert "\xF5" from ASCII-8BIT to UTF-8 for guides/assets/images/chapters_icon.gif, skipping
unable to convert "\xF5" from ASCII-8BIT to UTF-8 for guides/assets/images/check_bullet.gif, skipping
unable to convert "\xF4" from ASCII-8BIT to UTF-8 for guides/assets/images/credits_pic_blank.gif, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/csrf.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/edge_badge.png, skipping
unable to convert "\x9E" from ASCII-8BIT to UTF-8 for guides/assets/images/favicon.ico, skipping
unable to convert "\x80" from ASCII-8BIT to UTF-8 for guides/assets/images/feature_tile.gif, skipping
unable to convert "\x80" from ASCII-8BIT to UTF-8 for guides/assets/images/footer_tile.gif, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/fxn.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/challenge.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/confirm_dialog.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/forbidden_attributes_for_new_post.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/form_with_errors.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/index_action_with_edit_link.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/new_post.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/post_with_comments.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/rails_welcome.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/routing_error_no_controller.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/routing_error_no_route_matches.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/show_action_for_posts.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/template_is_missing_posts_new.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/undefined_method_post_path.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/unknown_action_create_for_posts.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/getting_started/unknown_action_new_for_posts.png, skipping
unable to convert "\xF0" from ASCII-8BIT to UTF-8 for guides/assets/images/grey_bullet.gif, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/habtm.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/has_many.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/has_many_through.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/has_one.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/has_one_through.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/header_backdrop.png, skipping
unable to convert "\x80" from ASCII-8BIT to UTF-8 for guides/assets/images/header_tile.gif, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/i18n/demo_html_safe.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/i18n/demo_localized_pirate.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/i18n/demo_translated_en.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/i18n/demo_translated_pirate.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/i18n/demo_translation_missing.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/i18n/demo_untranslated.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/1.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/10.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/11.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/12.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/13.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/14.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/15.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/2.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/3.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/4.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/5.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/6.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/7.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/8.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/callouts/9.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/caution.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/example.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/home.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/important.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/next.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/note.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/prev.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/tip.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/up.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/icons/warning.png, skipping
unable to convert "\xFF" from ASCII-8BIT to UTF-8 for guides/assets/images/jaimeiniesta.jpg, skipping
unable to convert "\xF5" from ASCII-8BIT to UTF-8 for guides/assets/images/nav_arrow.gif, skipping
unable to convert "\xFF" from ASCII-8BIT to UTF-8 for guides/assets/images/oscardelben.jpg, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/polymorphic.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/radar.png, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/rails4_features.png, skipping
unable to convert "\xFF" from ASCII-8BIT to UTF-8 for guides/assets/images/rails_guides_kindle_cover.jpg, skipping
unable to convert "\xEC" from ASCII-8BIT to UTF-8 for guides/assets/images/rails_guides_logo.gif, skipping
unable to convert "\x8C" from ASCII-8BIT to UTF-8 for guides/assets/images/rails_logo_remix.gif, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/session_fixation.png, skipping
unable to convert "\x80" from ASCII-8BIT to UTF-8 for guides/assets/images/tab_grey.gif, skipping
unable to convert "\x80" from ASCII-8BIT to UTF-8 for guides/assets/images/tab_info.gif, skipping
unable to convert "\x80" from ASCII-8BIT to UTF-8 for guides/assets/images/tab_note.gif, skipping
unable to convert "\x80" from ASCII-8BIT to UTF-8 for guides/assets/images/tab_red.gif, skipping
unable to convert "\x80" from ASCII-8BIT to UTF-8 for guides/assets/images/tab_yellow.gif, skipping
unable to convert "\x89" from ASCII-8BIT to UTF-8 for guides/assets/images/tab_yellow.png, skipping
unable to convert "\xFF" from ASCII-8BIT to UTF-8 for guides/assets/images/vijaydev.jpg, skipping
1 gem installed

Then I re-run rails -v:

$ rails -v 
Rails is not currently installed on this system. To get the latest version, simply type:

    $ sudo gem install rails

You can then rerun your "rails" command.

Same result. Question: What did I miss?

Additional Information of rvm:

$ rvm -v

rvm 1.21.10 (stable) by Wayne E. Seguin <[email protected]>, Michal Papis <[email protected]> [https://rvm.io/]

Note: My Mac OS X is 10.7.5, and my account has admin rights. Current directory is ~ (home directory)

UPDATE: Here are the outputs based on the comments :

$ gem -v
2.0.5
$ which gem
/Users/MyUserName/.rvm/rubies/ruby-2.0.0-p247/bin/gem

what should I do next ?

As mentioned in my comment, first make sure that both ruby and gem point to the RVM-installed versions, and not the ones in /usr/bin.

Also make sure you use your new Ruby as default:

rvm --default use 2.0.0-p247

Create a Gemset (called gemset) that will be used for this Ruby version:

rvm use 2.0.0-p247@gemset --create --default

Then install Rails to that Gemset:

gem install rails

This should be enough to use the new rails version. Try restarting your shell if it doesn't stick.