title: How to interleave lines from two text files
body: <p>What's the easiest/quickest way to interleave the lines of two (or more) text files? Example:</p>
  
  <p>File 1:</p>
  
  <pre><code>line1.1
  line1.2
  line1.3
  </code></pre>
  
  <p>File 2:</p>
  
  <pre><code>line2.1
  line2.2
  line2.3
  </code></pre>
  
  <p>Interleaved:</p>
  
  <pre><code>line1.1
  line2.1
  line1.2
  line2.2
  line1.3
  line2.3
  </code></pre>
  
  <p>Sure it's easy to write a little Perl script that opens them both and does the task. But I was wondering if it's possible to get away with fewer code, maybe a one-liner using Unix tools?</p>