gem install mysql sqlite3-ruby nokogiri 错误

$ gem install mysql2 
Building native extensions.  This could take a while... 
ERROR:  Error installing mysql2: 
        ERROR: Failed to build gem native extension. 

=============8<==ubuntu  错误解决办法==========
sudo apt-get install libmysql-ruby libmysqlclient-dev 




****************=<*******************
#gem install nokigiri

ERROR:  While executing gem ... (Gem::RemoteFetcher::FetchError)

Building native extensions.  This could take a while...
ERROR:  Error installing nokogiri:
    ERROR: Failed to build gem native extension.


================8<==================
http://nokogiri.org/tutorials/installing_nokogiri.html

$sudo apt-get install libxslt-dev libxml2-dev

$sudo gem install nokogiri -v '1.5.5'



=========*<===========

apt-get install libsqlite3-dev