title: How to insert a text at the beginning of a file?
body: <p>So far I've been able to find out how to add a line at the beginning of a file but that's not exactly what I want. I'll show it with an example:</p>
  <p><strong>File content</strong></p>
  <pre><code>some text at the beginning
  </code></pre>
  <p><strong>Result</strong></p>
  <pre><code>&lt;added text&gt; some text at the beginning
  </code></pre>
  <p>It's similar but I don't want to create any new line with it...</p>
  <p>I would like to do this with <code>sed</code> if possible.</p>