Here is a pro tip I never thought I would need to share!

For Nokogiri to install on OSx out of the box it requires some of the command line tools that come with xCode. I have everything like that installed because I have had to install things like Nokogiri several times in the past.

Today though I was getting this error message that suggested that I didn't have those required tools installed.

Building native extensions.  This could take a while...
Building nokogiri using packaged libraries.
ERROR:  Error installing nokogiri:
	ERROR: Failed to build gem native extension.

    /Users/tobyosbourn/.rvm/rubies/ruby-2.1.1/bin/ruby extconf.rb
Building nokogiri using packaged libraries.
checking for iconv.h... *** 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.

10 minutes of yak shaving later and I decided to open up xCode to see what the craic was, turns out a point release had been downloaded and installed and came with a new EULA, as soon as I accepted this I was able to install the nokogiri gem successfully!