При попытке установить heroku появляется следующая ошибка.
arun@laptop:~/apps/pm$ sudo gem install heroku
Building native extensions. This could take a while...
ERROR: Error installing heroku:
ERROR: Failed to build gem native extension.
/usr/bin/ruby1.8 extconf.rb
extconf.rb:1:in `require': no such file to load -- mkmf (LoadError)
from extconf.rb:1
Gem files will remain installed in /var/lib/gems/1.8/gems/json-1.4.6 for inspection.
Results logged to /var/lib/gems/1.8/gems/json-1.4.6/ext/json/ext/generator/gem_make.out
arun@laptop:~/apps/pm$