我不知道如何修复这个错误。我安装了 libxml2，nokogiri 也安装正确。
Building native extensions. This could take a while...
ERROR: Error installing fog:
ERROR: Failed to build gem native extension.
/usr/bin/ruby extconf.rb
checking for libxml/parser.h... no
-----
libxml2 is missing. please visit http://nokogiri.org/tutorials/installing_nokogiri.html for help with installing dependencies.
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*** 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/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
Gem files will remain installed in /usr/lib64/ruby/gems/1.8/gems/nokogiri-1.5.10 for inspection.
Results logged to /usr/lib64/ruby/gems/1.8/gems/nokogiri-1.5.10/ext/nokogiri/gem_make.out
答案1
您需要安装 libxml-devel 包。每次看到这样的消息，都是由于依赖项中缺少头文件。在安装过程中，需要编译本机代码（C/C++），并且执行此操作需要头文件。
答案2
缺少 libxml2
您需要安装 libxml2 的开发包，例如
sudo apt-get install libxml2-dev
如果仍然失败，请在 Ubuntu 上尝试安装：
sudo apt-get install gcc ruby-dev libxslt-dev zlib1g-dev