title: Appending characters to the end of each line in Emacs
body: <p>Assume I have a text file with content</p>
  
  <pre><code>1
  123
  12
  12345
  </code></pre>
  
  <p>If I want to add an 'a' in the beginning of each line I can simply use string-rectangle (C-x r t), but what if I want to append an 'a' to the end of each line, after which the file should become</p>
  
  <pre><code>1a
  123a
  12a
  12345a
  </code></pre>
  
  <p>Thanks.</p>