title: How to install mysql2 on Ubuntu 16.04 [ ERROR: Error installing mysql2: ERROR: Failed to build gem native extension.]
body: <p>I don't know install mysql2 on ubuntu :( </p>
  
  <pre><code>sudo gem install mysql2
  Building native extensions.  This could take a while...
  ERROR:  Error installing mysql2:
  ERROR: Failed to build gem native extension.
  
  current directory: /var/lib/gems/2.3.0/gems/mysql2-0.4.4/ext/mysql2
  /usr/bin/ruby2.3 -r ./siteconf20160515-9715-1s2u1sj.rb extconf.rb
  mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h
  
  extconf failed, exit code 1
  
  Gem files will remain installed in /var/lib/gems/2.3.0/gems/mysql2-0.4.4 for inspection.
  Results logged to /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/mysql2-0.4.4/gem_make.out
  </code></pre>
  
  <p><strong>sudo apt-get install libmysqlclient-dev</strong></p>
  
  <pre><code>Lendo listas de pacotes... Pronto
  Construindo árvore de dependências       
  Lendo informação de estado... Pronto
  libmysqlclient-dev is already the newest version (5.7.12-0ubuntu1).
  0 pacotes atualizados, 0 pacotes novos instalados, 0 a serem removidos e 61 não atualizados.
  </code></pre>
  
  <p><strong>but is not working</strong></p>