使用“sudo gem install nokogiri”在mac上安装nokogiri时出错
我试图安装nokogiri，因为它是启动rails所必需的
$ rails s /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/spec_set.rb:90:in `block in materialize': Could not find nokogiri-1.5.5 in any of the sources (Bundler::GemNotFound) from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/spec_set.rb:83:in `map!' from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/spec_set.rb:83:in `materialize' from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/definition.rb:127:in `specs' from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/environment.rb:27:in `specs' from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/rubygems-bundler-1.0.3/lib/rubygems-bundler/noexec.rb:41:in `candidate?' from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/rubygems-bundler-1.0.3/lib/rubygems-bundler/noexec.rb:60:in `setup' from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/rubygems-bundler-1.0.3/lib/rubygems-bundler/noexec.rb:75:in `' from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:60:in `require' from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:60:in `rescue in require' from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:35:in `require' from /usr/local/rvm/gems/ruby-1.9.3-p194/bin/ruby_noexec_wrapper:9:in `' 但是，当我尝试使用该命令安装nokogiri时，它失败了
$ sudo gem install nokogiri
这是错误。
$ sudo gem install nokogiri Building native extensions. This could take a while... ERROR: Error installing nokogiri: ERROR: Failed to build gem native extension. /usr/local/rvm/rubies/ruby-1.9.3-p194/bin/ruby extconf.rb 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 --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-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-libiconv-config --without-libiconv-config /usr/local/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 /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:506:in `try_cpp' from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:970:in `block in find_header' from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:790:in `block in checking_for' from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:284:in `block (2 levels) in postpone' from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:254:in `open' from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:284:in `block in postpone' from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:254:in `open' from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:280:in `postpone' from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:789:in `checking_for' from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:969:in `find_header' from extconf.rb:114:in `' Gem files will remain installed in /usr/local/rvm/gems/ruby-1.9.3-p194/gems/nokogiri-1.5.5 for inspection. Results logged to /usr/local/rvm/gems/ruby-1.9.3-p194/gems/nokogiri-1.5.5/ext/nokogiri/gem_make.out
看起来你需要安装Xcode。
您收到此错误的原因是因为nokogiri gem包含需要在您的计算机上运行之前需要编译的C / C ++扩展。
只是安装XCode不会修复它 – 您需要专门安装XCode命令行工具，这是一个C / C ++编译器/链接器工具链，在安装XCode时默认情况下不会安装。
可以选择在XCode GUI中的菜单中安装它们，请参阅此主题以获取屏幕截图：
Xcode 4.4及更高版本安装命令行工具
如果您已经这样做了，那么您可能需要创建一个指向编译器的符号链接，以便您的操作系统知道在哪里找到它：
安装nokogiri安装了Mac OS X 10.8.2 XCode