I installed the ruby 1.9.3. while instillation rails, I am getting instillation error. Below is the error
ERROR: Error installing rails: ERROR: Failed to build gem native extension.
/usr/bin/ruby1.9.1 extconf.rb /usr/local/lib/site_ruby/1.9.1/rubygems/core_ext/kernel_require.rb:45:in `require': cannot load such file -- mkmf (LoadError) from /usr/local/lib/site_ruby/1.9.1/rubygems/core_ext/kernel_require.rb:45:in `require' from extconf.rb:1:in `<main>'
Gem files will remain installed in /usr/lib/ruby/gems/1.9.1/gems/json-1.8.0 for inspection. Results logged to /usr/lib/ruby/gems/1.9.1/gems/json-1.8.0/ext/json/ext/generator/gem_make.out
Please anyone help me out