title: sed throws 'bad flag in substitute command'
body: <p>I want to run a simple command of replacing absolute paths to relative ones inside a CSS file like this:</p>
  
  <pre><code>sed -i 's/\/fonts/../fonts/' /Users/sergeybasharov/WebstormProjects/snap/compiled/Content/stylesheets/style.css
  </code></pre>
  
  <p>It throws this</p>
  
  <pre><code>sed: 1: "/Users/sergeybasharov/W ...": bad flag in substitute command: 'b'
  </code></pre>
  
  <p>What can be wrong in this simple script?</p>