顺便提一下,我可以通过卸载ruby 1.9.3并恢复到1.8.7来解决这个问题.然而,这显然是一个次优的解决方案,因为我不想在1.8.7的时间内停留…

Users-MacBook-Pro:sample_app user$ls
Gemfile     app     doc     script
Gemfile.lock    config      lib     spec
README.md   config.ru   log     tmp
Rakefile    db      public      vendor
Ravins-MacBook-Pro:sample_app user$bundle
Fetching gem Metadata from https://rubygems.org/.......
/Users/user/.rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.2.1/lib/bundler.rb:263: warning: Insecure world writable dir /usr/local in PATH,mode 040777
Using rake (0.9.2.2) 
Using i18n (0.6.1) 
Using multi_json (1.3.6) 
Using activesupport (3.2.8) 
Using builder (3.0.3) 
Using activemodel (3.2.8) 
Using erubis (2.7.0) 
Using journey (1.0.4) 
Using rack (1.4.1) 
Using rack-cache (1.2) 
Using rack-test (0.6.2) 
Using hike (1.2.1) 
Using tilt (1.3.3) 
Using sprockets (2.1.3) 
Using actionpack (3.2.8) 
Using mime-types (1.19) 
Using polyglot (0.3.3) 
Using treetop (1.4.10) 
Using mail (2.4.4) 
Using actionmailer (3.2.8) 
Using arel (3.0.2) 
Using tzinfo (0.3.33) 
Using activerecord (3.2.8) 
Using activeresource (3.2.8) 
Using addressable (2.3.2) 
Installing nokogiri (1.5.5) with native extensions 
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

        /Users/user/.rvm/rubies/ruby-1.9.3-p194/bin/ruby extconf.rb 
extconf.rb:86: warning: Insecure world writable dir /usr/local in PATH,mode 040777
checking for libxml/parser.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=/Users/user/.rvm/rubies/ruby-1.9.3-p194/bin/ruby
    --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-iconv-dir
    --without-iconv-dir
    --with-iconv-include
    --without-iconv-include=${iconv-dir}/include
    --with-iconv-lib
    --without-iconv-lib=${iconv-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-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-pkg-config
    --without-pkg-config
    --with-libxml-2.0-config
    --without-libxml-2.0-config
    --with-pkg-config
    --without-pkg-config
    --with-libiconv-config
    --without-libiconv-config
    --with-pkg-config
    --without-pkg-config
/Users/user/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:381:in `try_do': The compiler Failed to generate an executable file. (RuntimeError)
You have to install development tools first.
    from /Users/user/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:506:in `try_cpp'
    from /Users/user/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:970:in `block in find_header'
    from /Users/user/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:790:in `block in checking_for'
    from /Users/user/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:284:in `block (2 levels) in postpone'
    from /Users/user/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:254:in `open'
    from /Users/user/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:284:in `block in postpone'
    from /Users/user/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:254:in `open'
    from /Users/user/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:280:in `postpone'
    from /Users/user/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:789:in `checking_for'
    from /Users/user/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:969:in `find_header'
    from extconf.rb:114:in `<main>'


Gem files will remain installed in /Users/user/.rvm/gems/ruby-1.9.3-p194/gems/nokogiri-1.5.5 for inspection.
Results logged to /Users/user/.rvm/gems/ruby-1.9.3-p194/gems/nokogiri-1.5.5/ext/nokogiri/gem_make.out
An error occurred while installing nokogiri (1.5.5),and Bundler cannot continue.
Make sure that `gem install nokogiri -v '1.5.5'` succeeds before bundling.

我已经下载了XCODE,包括开发工具,所以我不知道为什么它不会安装nokogiri …

当我尝试直接安装nokogiri,我得到：

ERROR:  Error installing nokogiri:
    ERROR: Failed to build gem native extension.

        /Users/ravinthambapillai/.rvm/rubies/ruby-1.9.3-p194/bin/ruby extconf.rb
extconf.rb:86: warning: Insecure world writable dir /usr/local in PATH,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=/Users/ravinthambapillai/.rvm/rubies/ruby-1.9.3-p194/bin/ruby
    --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-iconv-dir
    --without-iconv-dir
    --with-iconv-include
    --without-iconv-include=${iconv-dir}/include
    --with-iconv-lib
    --without-iconv-lib=${iconv-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-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-pkg-config
    --without-pkg-config
    --with-libxml-2.0-config
    --without-libxml-2.0-config
    --with-pkg-config
    --without-pkg-config
    --with-libiconv-config
    --without-libiconv-config
    --with-pkg-config
    --without-pkg-config
/Users/ravinthambapillai/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:381:in `try_do': The compiler Failed to generate an executable file. (RuntimeError)
You have to install development tools first.
    from /Users/ravinthambapillai/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:506:in `try_cpp'
    from /Users/ravinthambapillai/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:970:in `block in find_header'
    from /Users/ravinthambapillai/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:790:in `block in checking_for'
    from /Users/ravinthambapillai/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:284:in `block (2 levels) in postpone'
    from /Users/ravinthambapillai/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:254:in `open'
    from /Users/ravinthambapillai/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:284:in `block in postpone'
    from /Users/ravinthambapillai/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:254:in `open'
    from /Users/ravinthambapillai/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:280:in `postpone'
    from /Users/ravinthambapillai/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:789:in `checking_for'
    from /Users/ravinthambapillai/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:969:in `find_header'
    from extconf.rb:114:in `<main>'


Gem files will remain installed in /Users/ravinthambapillai/.rvm/gems/ruby-1.9.3-p194/gems/nokogiri-1.5.5 for inspection.
Results logged to /Users/ravinthambapillai/.rvm/gems/ruby-1.9.3-p194/gems/nokogiri-1.5.5/ext/nokogiri/gem_make.out

谢谢,