Rubygems do not install on OS X Lion

Question

I used to have no problems at all with ruby, gems and all related stuff. But after installing X Code Developer Tools and upgrading to Lion the gems do not install.

I get the following error for every gem. This is the message for sqlite as an example:

Building native extensions.  This could take a while... ERROR:  Error installing sqlite3: 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/sqlite3-1.3.4 for inspection. Results logged to /Library/Ruby/Gems/1.8/gems/sqlite3-1.3.4/ext/sqlite3/gem_make.out 

What went wrong? How to fix it?

Answer 1

I had to install the Command Line Tools in the latest Xcode-Version (4.3.1) and

sudo gem install rails 

worked like a charm.

To install Command Line Tools, go to Xcode Preferences > Downloads or use the following command in terminal (thx @Purell):

xcode-select --install 

Answer 2

I'm using Mavericks and Ruby 2.0.0 and I also got this error (mkmf.rb can't find header files) when installing gems. I solved this issue by creating some symbolic links in Terminal.

#First install developer tools again: xcode-select --install  #Create symbolic link to Ruby include (updated for 10.9) sudo ln -s /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/include/ruby-2.0.0 /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/include  #Create symbolic link to config.h (updated for 10.9) sudo ln -s /System/Library/Frameworks/Ruby.framework/Versions/2.0/Headers/ruby/config.h /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/include/ruby-2.0.0/ruby/config.h