title: argument "destdir" is missing, with no default
body: <p>In my Linux Mint 17 terminal, I start <code>R</code> simple by typing:</p>
  
  <pre><code>&gt; R
  </code></pre>
  
  <p>Then, when I do <code>install.packages('foo')</code>, I get:</p>
  
  <pre><code>argument "destdir" is missing, with no default
  </code></pre>
  
  <p>How should I choose my <code>destdir</code>? And why is it not set by default?</p>