我无法安装指南针版本 1。
$ ruby -v
ruby 1.9.3p0 (2011-10-30 revision 33570) [x86_64-linux]
当我这样做的时候：
$ sudo gem install compass --pre
我收到以下错误：
Building native extensions. This could take a while...
ERROR: Error installing compass:
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:4:in `<main>'
Gem files will remain installed in /var/lib/gems/1.9.1/gems/ffi-1.9.3 for inspection.
Results logged to /var/lib/gems/1.9.1/gems/ffi-1.9.3/ext/ffi_c/gem_make.out
知道如何修复此问题吗？我正在使用 Ubuntu 12.04 LTS。