sudo gem install nokogiri
Ubuntu 12.1で実行すると、これが返されます。何が問題で、どうすれば修正できますか?
jason@jason:~/ror/clss$ sudo gem install nokogiri
Building native extensions. This could take a while...
ERROR: Error installing nokogiri:
ERROR: Failed to build gem native extension.
/usr/bin/ruby1.9.1 extconf.rb
/usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load such file
-- mkmf (LoadError)
from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
from extconf.rb:5:in `<main>'
Gem files will remain installed in /var/lib/gems/1.9.1/gems/nokogiri-1.5.5 for
inspection. Results logged to /var/lib/gems/1.9.1/gems/nokogiri-1.5.5/ext/nokogiri
/gem_make.out