title: Linux command to find similarity in two text files.If both have matching tring, push it to a text file
body: <p>file1.txt</p>
  <blockquote>
  <p>Message Id:4401811003996404</p>
  </blockquote>
  <p>file2.txt</p>
  <blockquote>
  <p>Message Id:4401811003996404 End Time</p>
  <p>Message Id:4401811007868646 End Time</p>
  </blockquote>
  <p>I tried to use cut to trim the End Time from the <code>file2.txt</code> but it cut digits too.</p>
  <p>Also tried comm -12 <code>file1.txt</code> and <code>file2.txt</code>, output was blank.</p>
  <p>I want output something like this</p>
  <blockquote>
  <p>Message Id:4401811003996404</p>
  </blockquote>