Install Nokogiri on Yosemite 10.10.3 - ruby

Question

I have:
Mac OS X Yosemite 10.10.3
MacPorts (not Brew)
Ruby 2 in system (not RVM)
I want to install Nokogiri and tried:
port install nokogiri
and got:
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
./siteconf20150323-30174-1mqhl4i.rb extconf.rb checking if the C
compiler accepts ... yes checking if the C compiler accepts
-Wno-error=unused-command-line-argument-hard-error-in-future... no Building nokogiri using packaged libraries. checking for gzdopen() in
-lz... yes checking for iconv... yes
************************************************************************ IMPORTANT NOTICE:
Building Nokogiri with a packaged version of libxml2-2.9.2 with the
following patches applied:
- 0001-Revert-Missing-initialization-for-the-catalog-module.patch
- 0002-Fix-missing-entities-after-CVE-2014-3660-fix.patch
Team Nokogiri will keep on doing their best to provide security
updates in a timely manner, but if this is a concern for you and want
to use the system library instead; abort this installation process and
reinstall nokogiri as follows:
gem install nokogiri -- --use-system-libraries
[--with-xml2-config=/path/to/xml2-config]
[--with-xslt-config=/path/to/xslt-config]
If you are using Bundler, tell it to use the option:
bundle config build.nokogiri --use-system-libraries
bundle install
Note, however, that nokogiri is not fully compatible with arbitrary
versions of libxml2 provided by OS/package vendors.
************************************************************************ Extracting libxml2-2.9.2.tar.gz into
tmp/x86_64-apple-darwin14/ports/libxml2/2.9.2... OK Running patch with
/Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.6.2/ports/patches/libxml2/0001-Revert-Missing-initialization-for-the-catalog-module.patch...
Running 'patch' for libxml2 2.9.2... OK Running patch with
/Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.6.2/ports/patches/libxml2/0002-Fix-missing-entities-after-CVE-2014-3660-fix.patch...
Running 'patch' for libxml2 2.9.2... OK Running 'configure' for
libxml2 2.9.2... OK Running 'compile' for libxml2 2.9.2... ERROR,
review
'/Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.6.2/ext/nokogiri/tmp/x86_64-apple-darwin14/ports/libxml2/2.9.2/compile.log'
to see what happened.
*** 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
--help --clean --use-system-libraries --enable-static
--disable-static --with-zlib-dir --without-zlib-dir
--with-zlib-include --without-zlib-include=${zlib-dir}/include
--with-zlib-lib --without-zlib-lib=${zlib-dir}/lib
--enable-cross-build --disable-cross-build
/Library/Ruby/Gems/2.0.0/gems/mini_portile-0.6.2/lib/mini_portile.rb:279:in
`block in execute': Failed to complete compile task (RuntimeError)
from
/Library/Ruby/Gems/2.0.0/gems/mini_portile-0.6.2/lib/mini_portile.rb:271:in
`chdir' from
/Library/Ruby/Gems/2.0.0/gems/mini_portile-0.6.2/lib/mini_portile.rb:271:in
`execute' from
/Library/Ruby/Gems/2.0.0/gems/mini_portile-0.6.2/lib/mini_portile.rb:70:in
`compile' from
/Library/Ruby/Gems/2.0.0/gems/mini_portile-0.6.2/lib/mini_portile.rb:110:in
`cook' from extconf.rb:278:in `block in process_recipe' from
extconf.rb:177:in `tap' from extconf.rb:177:in `process_recipe' from
extconf.rb:475:in `<main>'
extconf failed, exit code 1
Gem files will remain installed in
/Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.6.2 for inspection. Results
logged to
/Library/Ruby/Gems/2.0.0/extensions/universal-darwin-14/2.0.0/nokogiri-1.6.6.2/gem_make.out
I tried:
gem install nokogiri -- --use-system-libraries
and got:
Building native extensions with: '--use-system-libraries' 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
./siteconf20150323-34882-16v74a8.rb extconf.rb --use-system-libraries
checking if the C compiler accepts ... yes checking if the C compiler
accepts
-Wno-error=unused-command-line-argument-hard-error-in-future... no Building nokogiri using system libraries. checking for xmlParseDoc()
in libxml/parser.h... no checking for xmlParseDoc() in -lxml2... no
checking for xmlParseDoc() in -llibxml2... no
----- libxml2 is missing. Please locate mkmf.log to investigate how it is failing.
-----
*** 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
--help --clean --use-system-libraries --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-xml2-dir
--without-xml2-dir --with-xml2-include
--without-xml2-include=${xml2-dir}/include --with-xml2-lib
--without-xml2-lib=${xml2-dir}/lib --with-libxml-2.0-config
--without-libxml-2.0-config --with-pkg-config --without-pkg-config
--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-exslt-dir --without-exslt-dir
--with-exslt-include --without-exslt-include=${exslt-dir}/include
--with-exslt-lib --without-exslt-lib=${exslt-dir}/lib
--with-libexslt-config --without-libexslt-config --with-xml2lib
--without-xml2lib --with-libxml2lib --without-libxml2lib
extconf failed, exit code 1
Gem files will remain installed in
/Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.6.2 for inspection. Results
logged to
/Library/Ruby/Gems/2.0.0/extensions/universal-darwin-14/2.0.0/nokogiri-1.6.6.2/gem_make.out
I tried:
port install libxml2
and got:
---> Computing dependencies for libxml2
---> Cleaning libxml2
---> Scanning binaries for linking errors
---> No broken files found.
What else I can do to install Nokogiri?

Answer 1

Because MacPorts (and other similar package managers) install packages in non-standard locations, it cannot automatically determine the path to libxml2. The warning in your first attempt provided information on how to resolve this:
gem install nokogiri -- --use-system-libraries
[--with-xml2-config=/path/to/xml2-config]
[--with-xslt-config=/path/to/xslt-config]
You said that you tried gem install nokogiri -- --use-system-libraries. The Nokogiri documentation suggests that you need to add either of the following two options:
--with-xml2-config - Path to the xml2-config binary (try which xml2-config)
--with-xml2-dir - Path to the libxml2 base installation directory
If you’ve got libxml2 and/or libxslt installed in a nonstandard place
(read as “not /opt/local, /usr/local, /usr or the standard Ruby
directories”), you can use command-line parameters to the gem install
command to grease the wheels.
gem install nokogiri -- \
--use-system-libraries \
--with-xml2-dir=/path/to/dir \
--with-xslt-dir=/path/to/dir
This page gives appropriate commands for various package managers, including MacPorts:
gem install nokogiri -- \
--with-xml2-include=/opt/local/include/libxml2 \
--with-xml2-lib=/opt/local/lib \
--with-xslt-dir=/opt/local

Answer 2

Check to see if Xcode is installed on your machine then run xcode-select --install in the terminal. This should do the trick and allow you to run sudo gem install rails