title: Copying last n lines to a new file and then removing the n lines from original
body: <p>So I have a file where I want to move the last 3000 lines to another different file, and then create a new file from the original without the last 3000 lines.</p>
  
  <p>I'm using a Mac and the command I used is as follows:</p>
  
  <pre><code>tail -n 3000 fer2017-testing-reduced.arff &gt;&gt; fer2017-training-reduced-3000-more-instances.arff; head -n -3000 fer2017-testing-reduced.arff &gt; fer2017-testing-reduced-3000-less-instances.arff
  </code></pre>
  
  <p>However when I run this, I get the error:</p>
  
  <pre><code>head: illegal line count -- -3000
  </code></pre>
  
  <p>I'm not sure where I've gone wrong, or if this may be a mac issue?</p>