title: Error Rails - libxml-Ruby
body: <p>I've been struggling with this error installing libxml-ruby while setting up my active merchant git. I've Googled all the components of the error many times, but I'm just not really sure what I'm looking at. There's a bunch of "no's" - anybody know how to interpret what I may be missing?</p>
  
  <pre><code>Building native extensions.  This could take a while...
  ERROR:  Error installing libxml-ruby:
  ERROR: Failed to build gem native extension.
  
  /Users/tommynicholas/.rvm/rubies/ruby-2.1.1/bin/ruby extconf.rb
  checking for socket() in -lsocket... no
  checking for gethostbyname() in -lnsl... no
  checking for atan() in -lm... yes
  checking for inflate() in -lz... yes
  checking for iconv_open() in -liconv... yes
  checking for xmlParseDoc() in -lxml2... yes
  checking for libxml/xmlversion.h... no
  checking for libxml/xmlversion.h in     /opt/include/libxml2,/usr/local/include/libxml2,/usr/include/libxml2... no
  *** 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/tommynicholas/.rvm/rubies/ruby-2.1.1/bin/ruby
  --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-zlib-dir
  --without-zlib-dir
  --with-zlib-include
  --without-zlib-include=${zlib-dir}/include
  --with-zlib-lib
  --without-zlib-lib=${zlib-dir}/lib
  --with-socketlib
  --without-socketlib
  --with-nsllib
  --without-nsllib
  --with-mlib
  --without-mlib
  --with-zlib
  --without-zlib
  --with-iconvlib
  --without-iconvlib
  --with-xml2-config
  --without-xml2-config
  --with-xml2lib
  --without-xml2lib
  extconf failure: need libxml2.
  
  Install the library or try one of the following options to extconf.rb:
  
    --with-xml2-config=/path/to/xml2-config
    --with-xml2-dir=/path/to/libxml2
    --with-xml2-lib=/path/to/libxml2/lib
    --with-xml2-include=/path/to/libxml2/include
  
  
  extconf failed, exit code 1
  
  Gem files will remain installed in /Users/tommynicholas/.rvm/rubies/ruby-    2.1.1/lib/ruby/gems/2.1.0/gems/libxml-ruby-2.7.0 for inspection.
  Results logged to /Users/tommynicholas/.rvm/rubies/ruby-    2.1.1/lib/ruby/gems/2.1.0/extensions/x86_64-darwin-13/2.1.0/libxml-ruby-2.7.0/gem_make.out
  </code></pre>