Quando executo o comando:
gem install rails --version=4.2.1
ocorre o seguinte erro:
Building native extensions. This could take a while... ERROR: Error installing rails: ERROR: Failed to build gem native extension.
current directory: /var/lib/gems/2.1.0/gems/nokogiri-1.6.7.2/ext/nokogiri /usr/bin/ruby2.1 -r ./siteconf20160525-3370-yy1m5u.rb extconf.rb mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h
extconf failed, exit code 1
Gem files will remain installed in /var/lib/gems/2.1.0/gems/nokogiri-1.6.7.2 for inspection. Results logged to /var/lib/gems/2.1.0/extensions/x86_64-linux/2.1.0/nokogiri-1.6.7.2/gem_make.out
Estou usando Ubuntu 15.10
