title: count all occurrences of string in a text file using grep, but with multiple search string
body: <p>I am using the below code to search using grep. If I am using only 1 search string, it works, but if with multiple search string, which is what I'm doing, it wont</p>
  
  <p>Using 1 search pattern</p>
  
  <pre><code>grep -o &lt;search string&gt; * | wc -l
  </code></pre>
  
  <p>Using multiple search pattern</p>
  
  <pre><code>grep -o '&lt;search string&gt;\|&lt;search string&gt;\|&lt;search string&gt;\|' *| wc -l
  </code></pre>
  
  <p>Is there something that I missed?</p>