title: how to check 2 conditions using while on linux
body: <p>when i do:</p>
  
  <pre><code>while [ $choice != 'X' ]
  do
  </code></pre>
  
  <p>it works but when i do</p>
  
  <pre><code>while [ $choice != 'x' ] || [ $choice != 'X' ]
  do
  </code></pre>
  
  <p>none of them work. </p>
  
  <p>Any idea?</p>