title: What does X11cairo followed by a number mean in R
body: <p>I  was wondering what does X11cairo in the following mean</p>
  
  <pre><code>&gt; pdf("1_4.pdf")
  &gt; plot(output)
  &gt; dev.off()
  X11cairo 
         2 
  </code></pre>
  
  <p>Also sometimes the number following X11cairo is 2, sometimes is 1. What does the number imply?</p>
  
  <p>Thanks!</p>