Fetching: rack-1.6.0.gem (100%)
Successfully installed rack-1.6.0
Fetching: rack-test-0.6.3.gem (100%)
Successfully installed rack-test-0.6.3
Building native extensions. This could take a while...
ERROR: Error installing rails:
ERROR: Failed to build gem native extension.
/Users/panerai/.rvm/rubies/ruby-1.9.3-p551/bin/ruby -r ./siteconf20150509-18953-vlw9j5.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.
The file "/usr/include/iconv.h" is missing in your build environment,
which means you haven't installed Xcode Command Line Tools properly.
To install Command Line Tools, try running `xcode-select --install` on
terminal and follow the instructions. If it fails, open Xcode.app,
select from the menu "Xcode" - "Open Developer Tool" - "More Developer
Tools" to open the developer site, download the installer for your OS
version and run it.
*** 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:
extconf failed, exit code 1
Gem files will remain installed in /Users/panerai/.rvm/gems/ruby-1.9.3-p551/gems/nokogiri-220.127.116.11 for inspection.
Results logged to /Users/panerai/.rvm/gems/ruby-1.9.3-p551/extensions/x86_64-darwin-14/1.9.1/nokogiri-18.104.22.168/gem_make.out