title: Replace string in a file if line starts with another string
body: <p>How can I replace a string in a file if line starts with another string using sed?</p>
  
  <p>For example, replace this line:</p>
  
  <pre><code>connection = sqlite://keystone:[YOURPASSWORD]@[YOURIP]/keystone
  </code></pre>
  
  <p>With this line:</p>
  
  <pre><code>connection = mysql://keystone:password@10.1.1.10/keystone
  </code></pre>