title: grep lines that start with a specific string
body: <p>I want to find all the lines in a file that start with a specific string. The problem is, I don't know what's in the string beforehand. The value is stored in a variable.</p>
  
  <p>The naïve solution would be the following:</p>
  
  <pre><code>grep "^${my_string}" file.txt;
  </code></pre>
  
  <p>Because if the Bash variable <code>my_string</code> contains ANY regular expression special characters, <code>grep</code> will cry, and everyone will have a bad day.</p>
  
  <p>You don't want to make <code>grep</code> cry, do you?</p>