title: How to write the xxd command in cmd in windows
body: <p>I am trying to use xxd command to convert string to hex. 
  I have typed this command in cmd in windows xxd -p &lt;&lt;&lt; "Hello world". 
  But I have got this in my cmd 
  'xxd' is not recognized as an internal or external command, operable program or batch file.</p>
  
  <p>How can I use xxd in cmd in windows? </p>
  
  <p>Thanks.</p>