title: Failing to install Nokogiri gem
body: <p>I'm working on a rails app that allows for image attachments to each use account. I'm using paperclip and amazon web services:</p>
  
  <pre><code>gem 'paperclip'
  gem 'aws-sdk'
  </code></pre>
  
  <p>When I run bundle install, I get this message: </p>
  
  <p>extconf failed, exit code 1</p>
  
  <pre><code>Gem files will remain installed in /usr/local/rvm/gems/ruby-2.1.2/gems/nokogiri-1.6.5 for inspection.
  Results logged to /usr/local/rvm/gems/ruby-2.1.2/extensions/x86_64-darwin-13/2.1.0-static/nokogiri-1.6.5/gem_make.out
  An error occurred while installing nokogiri (1.6.5), and Bundler cannot continue.
  Make sure that `gem install nokogiri -v '1.6.5'` succeeds before bundling.
  </code></pre>
  
  <p>When I try running 'gem install nokogiri', I get this message:</p>
  
  <p>extconf failed, exit code 1</p>
  
  <pre><code>Gem files will remain installed in /usr/local/rvm/gems/ruby-2.1.2/gems/nokogiri-1.6.5 for inspection.
  Results logged to /usr/local/rvm/gems/ruby-2.1.2/extensions/x86_64-darwin-13/2.1.0-static/nokogiri-1.6.5/gem_make.out
  </code></pre>
  
  <p>My OS is Mac OS X 10.9.4 Mavericks. <strong>What's going on here? How can I get nokogiri to install and behave properly?</strong></p>
  
  <p><strong>Full stack trace</strong>:</p>
  
  <pre><code>Building native extensions with: '--use-system-libraries'
  This could take a while...
  ERROR:  Error installing nokogiri:
      ERROR: Failed to build gem native extension.
  
      /usr/local/rvm/rubies/ruby-2.1.2/bin/ruby extconf.rb --use-system-libraries
  checking if the C compiler accepts ... yes
  checking if the C compiler accepts -Wno-error=unused-command-line-argument-hard-error-in-future... yes
  Building nokogiri using system libraries.
  libxml2 version 2.6.21 or later is required!
  *** 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=/usr/local/rvm/rubies/ruby-2.1.2/bin/ruby
      --help
      --clean
      --use-system-libraries
      --with-zlib-dir
      --without-zlib-dir
      --with-zlib-include
      --without-zlib-include=${zlib-dir}/include
      --with-zlib-lib
      --without-zlib-lib=${zlib-dir}/lib
      --with-xml2-dir
      --without-xml2-dir
      --with-xml2-include
      --without-xml2-include=${xml2-dir}/include
      --with-xml2-lib
      --without-xml2-lib=${xml2-dir}/lib
      --with-libxml-2.0-config
      --without-libxml-2.0-config
      --with-pkg-config
      --without-pkg-config
      --with-xslt-dir
      --without-xslt-dir
      --with-xslt-include
      --without-xslt-include=${xslt-dir}/include
      --with-xslt-lib
      --without-xslt-lib=${xslt-dir}/lib
      --with-libxslt-config
      --without-libxslt-config
      --with-exslt-dir
      --without-exslt-dir
      --with-exslt-include
      --without-exslt-include=${exslt-dir}/include
      --with-exslt-lib
      --without-exslt-lib=${exslt-dir}/lib
      --with-libexslt-config
      --without-libexslt-config
  
  extconf failed, exit code 1
  
  Gem files will remain installed in /usr/local/rvm/gems/ruby-2.1.2/gems/nokogiri-1.6.5 for inspection.
  Results logged to /usr/local/rvm/gems/ruby-2.1.2/extensions/x86_64-darwin-13/2.1.0-static/nokogiri-1.6.5/gem_make.out
  </code></pre>