title: How to assign complex expressions to variables using @ in shell
body: <p>I try to set value to variable indx by using another varibale lineId.</p>
  
  <pre><code>@ indx = ($lineId-1)*4 + 1
  </code></pre>
  
  <p>However, the above method can't work given the following error.</p>
  
  <pre class="lang-none prettyprint-override"><code>@: Badly formed number.
  </code></pre>
  
  <p>Instead, if split the single line to two, it works.</p>
  
  <pre><code>@ indx = $lineId - 1
  @ indx = $indx * 4 + 1
  </code></pre>
  
  <p>Thanks for pointing out my problem.</p>