title: Why shell base64 encode result is different from others?
body: <p>I'm to encode a string.</p>
  
  <p>First I used shell command:
  $ echo "teststring" | base64
  dGVzdHN0cmluZwo=</p>
  
  <p>But when I use a online tool, <a href="http://www.motobit.com/util/base64-decoder-encoder.asp" rel="noreferrer">http://www.motobit.com/util/base64-decoder-encoder.asp</a>
  the result is: dGVzdHN0cmluZw==</p>
  
  <p>Why are they different?</p>