cannot install RedCloth

Question

as in the title, i have problems installing gem RedCloth. i downloaded RubyGems v1.8.24, and use ubuntu 12.04, here is my console log:

kuba@kuba-P5Q-SE:~$ sudo gem install RedCloth
[sudo] password for kuba: 
Building native extensions.  This could take a while...
ERROR:  Error installing RedCloth:
    ERROR: Failed to build gem native extension.

        /usr/bin/ruby1.9.1 extconf.rb
/usr/local/lib/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load     such file -- mkmf (LoadError)
    from /usr/local/lib/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
    from extconf.rb:1:in `<main>'


Gem files will remain installed in /usr/lib/ruby/gems/1.9.1/gems/RedCloth-4.2.9 for     inspection.
Results logged to /usr/lib/ruby/gems/1.9.1/gems/RedCloth-    4.2.9/ext/redcloth_scan/gem_make.out

i tried to look into this last given file, but when i look for it, it opens chrome, and gives me error.:(

Answer 1

Try installing the ruby1.9.1-dev package from Synaptic, or using apt-get.

In a command prompt: sudo apt-get install ruby1.9.1-dev

mkmf (the module which is failing to load) is only included in the development package for ruby on ubuntu.