title: How to install library dependencies as a .tar.gz/.tar.xz archive on Travis CI?
body: <p>I'm using <a href="/questions/tagged/travis-ci" class="post-tag" title="show questions tagged &#39;travis-ci&#39;" rel="tag">travis-ci</a> to compile my program that uses <a href="/questions/tagged/sdl-2" class="post-tag" title="show questions tagged &#39;sdl-2&#39;" rel="tag">sdl-2</a>. The only problem is, I don't know how to actually install the packages <code>libsdl2</code> and <code>libsdl2-ttf</code> through <a href="/questions/tagged/travis-ci" class="post-tag" title="show questions tagged &#39;travis-ci&#39;" rel="tag">travis-ci</a>.</p>
  
  <p>Here's my config file:</p>
  
  <pre><code>language: cpp
  compiler: g++
  before_script:
    - mkdir -p build
  script: make all
  install:
    - wget http://archive.ubuntu.com/ubuntu/pool/universe/libs/libsdl2/libsdl2_2.0.4+dfsg2.orig.tar.gz
    - sudo tar -xzvf libsdl2_2.0.4+dfsg2.orig.tar.gz
    - wget http://archive.ubuntu.com/ubuntu/pool/universe/libs/libsdl2-ttf/libsdl2-ttf_2.0.12+dfsg1.orig.tar.xz
    - sudo tar xf libsdl2-ttf_2.0.12+dfsg1.orig.tar.xz
  </code></pre>
  
  <p>When the configuration is complete, it can't compile my program since it can't find <code>SDL2/SDL.h</code> which is in the <code>libsdl2</code> package.</p>