I’ve encountered the following error (and those like it) many, many times when setting up existing projects that use Nokogiri in conjunction with Homebrew. Every single time I encounter it, I have to sort through my history to try to find out how I solved it.

So this post is as much a reminder to myself as it is to other people experiencing the same issue.

When attempting to install the Nokogiri gem you might get an error similar to this:

  
Installing nokogiri (1.4.4) with native extensions 
/Users/carlos/.rvm/rubies/ree-1.8.7-2011.03/lib/ruby/site_ruby/1.8/rubygems/installer.rb:551:in `build_extensions': 
ERROR: Failed to build gem native extension. (Gem::Installer::ExtensionBuildError)

/Users/carlos/.rvm/rubies/ree-1.8.7-2011.03/bin/ruby extconf.rb
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... no
 

Here are the instructions that I use to solve the issue:

  
    brew install libxml2
    brew install libiconv
    brew link libiconv