安裝compass時出現ERROR: Failed to build gem native extension...... -- mkmf (Load Error)解決辦法

compass是一個css樣式框架。經過ruby gem能夠安裝它。
[sudo] gem install compass

在安裝時出現問題以下：

Fetching: sass-3.4.0.gem (100%)
    Fetching: multi_json-1.10.1.gem (100%)
    Fetching: compass-core-1.0.1.gem (100%)
    Fetching: compass-import-once-1.0.5.gem (100%)
    Fetching: chunky_png-1.3.1.gem (100%)
    Fetching: rb-fsevent-0.9.4.gem (100%)
    Fetching: ffi-1.9.3.gem (100%)
    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

查了一下解決辦法，上面找不到的文件mkmf是ruby1.9.1-dev包的一部分，因此把它安裝上就好。
sudo apt-get install ruby1.9.1-dev
接下來當即重試安裝compass，成功。

參考

啓發：stackoverflow上的解決辦法