title: remove part of string from each line
body: <p>I have a text file, where each line is a single string of the format</p>
  
  <pre><code>/home/usr1/284.txt
  </code></pre>
  
  <p>The whole file is like</p>
  
  <pre><code>/home/usr1/284.txt
  /home/usr1/361.txt
  </code></pre>
  
  <p>What I want is to remove <code>/home/usr1/</code> and keep the file name, e.g., <code>284.txt</code></p>
  
  <p>How to do that using linux/unix command?</p>