Problems installing Nokogiri -v 1.6.1 and libxml2 - ruby-on-rails

Question

I'm running Mac OSX "Yosemite", and I've been trying to install Nokogiri 1.6.1, but I keep running into the error below.
This is the error I ran into when I was trying to install Nokogiri 1.6.1:
sh-3.2# gem install nokogiri -v 1.6.1
Building native extensions. This could take a while...
ERROR: Error installing nokogiri:
ERROR: Failed to build gem native extension.
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby -r ./siteconf20150819-49747-fafnk9.rb extconf.rb
Extracting libxml2-2.8.0.tar.gz into tmp/x86_64-apple-darwin14.4.0/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 /Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.1/ports/x86_64-apple-darwin14.4.0/libxml2/2.8.0)...
Extracting libxslt-1.1.26.tar.gz into tmp/x86_64-apple-darwin14.4.0/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 /Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.1/ports/x86_64-apple-darwin14.4.0/libxslt/1.1.26)...
checking for libxml/parser.h... yes
checking for libxslt/xslt.h... yes
checking for libexslt/exslt.h... yes
checking for iconv_open() in iconv.h... no
checking for iconv_open() in -liconv... yes
checking for xmlParseDoc() in -lxml2... 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
--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=/System/Library/Frameworks/Ruby.framework/Versions/2.0/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
--with-iconvlib
--without-iconvlib
--with-xml2lib
--without-xml2lib
extconf failed, exit code 1
Gem files will remain installed in /Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.1 for inspection.
Results logged to /Library/Ruby/Gems/2.0.0/extensions/universal-darwin-14/2.0.0/nokogiri-1.6.1/gem_make.out
I tried everything on http://www.nokogiri.org/tutorials/installing_nokogiri.html, but I have been unsuccessful. I tried to install libxml2 to install Nokogiri 1.6.1, but my terminal says:
Cowardly refusing to `sudo brew install`

Answer 1

Sometimes installing Nokogiri is tricky as it has several dependencies, which is what happened in your case too.
"Installing Nokogiri" is a step-by-step tutorial on how to install Nokogiri on your Mac OSX system.

Answer 2

You need to install Package first
xcode-select --install
then
gem install nokogiri