title: How can I find unique characters per line of input?
body: <p>Is there any way to extract the unique characters of each line?</p>
  
  <p>I know I can find the unique lines of a file using</p>
  
  <pre><code>sort -u file
  </code></pre>
  
  <p>I would like to determine the unique characters of each line (something like <code>sort -u</code> for each line).</p>
  
  <p>To clarify: given this input:</p>
  
  <pre><code>111223234213
  111111111111
  123123123213
  121212122212
  </code></pre>
  
  <p>I would like to get this output:</p>
  
  <pre><code>1234
  1
  123
  12
  </code></pre>