macOS, Rails: "Failed to build gem native extension"

Question

I'm stuck trying to install rails on my mac. I have OS X 10.6.8 and I have confirmed that I have Ruby, version 1.8.7

I ran sudo gem update and sudo gem update --system to get the latest versions of the software.

However, when I run sudo gem install rails I get this error:

ERROR:  Error installing rails:
ERROR: Failed to build gem native extension.

/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb
mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/ruby.h


Gem files will remain installed in /Library/Ruby/Gems/1.8/gems/json-1.6.3 for inspection.
Results logged to /Library/Ruby/Gems/1.8/gems/json-1.6.3/ext/json/ext/parser/gem_make.out

Answer 1

If you have XCode 4 or later you will need to open it and go to Preferences -> Downloads -> Components and install the Command Line tools as they aren't installed by default. Couldn't install Rails until this happened.

Answer 2

Im using osx 10.10. You can download from the command-line

xcode-select --install

Answer 3

Not sure what it needs to compile, but OSX can't compile any native ruby extensions at all unless the Apple developer tools are installed. On 10.7 Lion you can download it free from the app store, or Download it here for 10.6: http://developer.apple.com/xcode/index.php

It may also be on your OSX install discs, though probably much more out of date.

Answer 4

Did you install the OS X developer tools? You'll need to do this to be able to build native extensions