为什么“gem install”可以，而“bundle install”不行?

Question

当我运行bundle install时，我得到了以下错误:

An error occurred while installing nokogiri (1.6.1), and Bundler cannot continue.
Make sure that `gem install nokogiri -v '1.6.1'` succeeds before bundling.

所以我试过

 gem install nokogiri -v '1.6.1'

这确实有效。现在当然这应该让我高兴，但我现在想知道，到底是什么做到了这一点，所以我可以安装gem，现在bundle install也成功了。

我正在运行Mac OSX 10.9.2。

这是我第一次运行bundle install时的日志

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
    /Users/me/.rvm/rubies/ruby-1.9.3-p545/bin/ruby extconf.rb --with-xml2-dir=/usr --with-xslt-dir=/opt/local --with-iconv-dir=/opt/local
Extracting libxml2-2.8.0.tar.gz into tmp/x86_64-apple-darwin13.1.0/ports/libxml2/2.8.0... OK
Running 'configure' for libxml2 2.8.0... OK
Running 'compile' for libxml2 2.8.0... OK
Running 'install' for libxml2 2.8.0... OK
Activating libxml2 2.8.0 (from /Users/me/.rvm/gems/ruby-1.9.3-p545/gems/nokogiri-1.6.1/ports/x86_64-apple-darwin13.1.0/libxml2/2.8.0)...
Extracting libxslt-1.1.26.tar.gz into tmp/x86_64-apple-darwin13.1.0/ports/libxslt/1.1.26... OK
Running 'configure' for libxslt 1.1.26... OK
Running 'compile' for libxslt 1.1.26... OK
Running 'install' for libxslt 1.1.26... OK
Activating libxslt 1.1.26 (from /Users/me/.rvm/gems/ruby-1.9.3-p545/gems/nokogiri-1.6.1/ports/x86_64-apple-darwin13.1.0/libxslt/1.1.26)...
checking for libxml/parser.h... no
-----
libxml2 is missing.  please visit http://nokogiri.org/tutorials/installing_nokogiri.html for help with installing dependencies.
-----
*** 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=/Users/me/.rvm/rubies/ruby-1.9.3-p545/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
    --with-iconv-include
    --without-iconv-include=${iconv-dir}/include
    --with-iconv-lib
    --without-iconv-lib=${iconv-dir}/lib
    --with-xml2-dir
    --with-xml2-include
    --without-xml2-include=${xml2-dir}/include
    --with-xml2-lib
    --without-xml2-lib=${xml2-dir}/lib
    --with-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
extconf failed, exit code 1
Gem files will remain installed in /Users/me/.rvm/gems/ruby-1.9.3-p545/gems/nokogiri-1.6.1 for inspection.
Results logged to /Users/me/.rvm/gems/ruby-1.9.3-p545/extensions/x86_64-darwin-13/1.9.1/nokogiri-1.6.1/gem_make.out

Answer 1

试试这个:

brew install libxml2 libxslt libiconv

你不能只通过bundle install安装它的原因是bundler只处理gem依赖关系，而不是本地依赖关系。gem要求你的系统拥有libxml2，而你却没有。所以你需要安装它们。提示我的答案的东西是你的日志中的这个错误信息:

 ERROR: Failed to build gem native extension.