title: Bash: How to use sed to remove all characters except letters and numbers?
body: <p>First off, I'm still learning about regular expression, I have googled about this but still doesn't work.</p>
  
  <p>How do I remove all characters except letters and numbers in a variable with <code>sed</code>? For example I have this text file:</p>
  
  <pre><code>MytextOnly !@#!text@@32423#@$text#%$#text%#t23432ext$32342%^-_+-=-_++_;:"'][}}{|\/
  </code></pre>
  
  <p>How do I show only letters and numbers?</p>