OS X Lion, Attempting Nokogiri install - libxml2 is missing

In Mavericks, installing the libraries with Homebrew and setting NOKOGIRI_USE_SYSTEM_LIBRARIES=1 before installing the gem did the trick for me.

Summarising:

• If previously installed, uninstall the gem:
  $ gem uninstall nokogiri

• Use Homebrew to install libxml2, libxslt and libiconv:
  $ brew install libxml2 libxslt libiconv

• Install the gem specifying the paths to the libraries to be linked against:
  $ NOKOGIRI_USE_SYSTEM_LIBRARIES=1 gem install nokogiri -- --use-system-libraries --with-iconv-dir="$(brew --prefix libiconv)" --with-xml2-config="$(brew --prefix libxml2)/bin/xml2-config" --with-xslt-config="$(brew --prefix libxslt)/bin/xslt-config"

Absolutely none of the other answers here worked for me.

On the latest version of Mavericks, the only method that succeeded for me was the following:

$ brew install libxml2 libxslt libiconv$ sudo gem install nokogiri -v '1.6.5' -- --use-system-libraries --with-xml2-include=/usr/include/libxml2 --with-xml2-lib=/usr/lib

Same issue happened to me on Lion. Took hours of reading posts, trying homebrew, macports, etc. When I found this post and read the contents of .rvm/gems/ruby-1.8.7-p358/gems/nokogiri-1.4.4/ext/nokogiri/mkmf.log, I saw:

find_header: checking for libxml/parser.h... -------------------- no"/usr/bin/gcc-4.2 -E -I. -I/Users/me/.rvm/rubies/ruby-1.8.7-p358/lib/ruby/1.8/i686-darwin10.8.0 -I. -I-I-I/opt/local/include -I-I-I/usr/local/include -I-I-I/Users/me/.rvm/rubies/ruby-1.8.7-p358/include -I-I-I/usr/include -I-I-I/usr/include/libxml2 -I/opt/local/include/libxml2 -I/usr/local/include/libxml2 -I/Users/me/.rvm/rubies/ruby-1.8.7-p358/include/libxml2 -I-I/opt/local/include -I-I/usr/local/include -I-I/Users/me/.rvm/rubies/ruby-1.8.7-p358/include -I-I/usr/include -I-I/usr/include/libxml2 -I/opt/local/include -I/usr/local/include -I/Users/me/.rvm/rubies/ruby-1.8.7-p358/include -I/usr/include -I/usr/include/libxml2  -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE   -g -O2  -fno-common -pipe -fno-common    -g -DXP_UNIX -O3 -Wall -Wcast-qual -Wwrite-strings -Wconversion -Wmissing-noreturn -Winline  conftest.c -o conftest.i"checked program was:/* begin */1: #include <libxml/parser.h>/* end */

However, gcc-4.2 didn't exist:

$ ls /usr/bin/gcc*/usr/bin/gcc

Hence, I was able to solve the issue and get nokogiri to install by making a gcc-4.2 a symlink to gcc.

sudo ln -s gcc gcc-4.2