title: sed replace string with space and special characters
body: <p>The test23 file contains a line</p>
  
  <pre><code>root_url = %(protocol)s://%(domain)s:%(http_port)s/
  </code></pre>
  
  <p>I need to replace this with </p>
  
  <pre><code>root_url = %(protocol)s://%(domain)s:%(http_port)s/grafana
  </code></pre>
  
  <p>This below steps in the script doesn't work. </p>
  
  <pre><code>line_old='root_url = %(protocol)s://%(domain)s:%(http_port)s/'
  line_new='root_url = %(protocol)s://%(domain)s:%(http_port)s/grafana'
  sed -i "s/\${line_old}\/\${line_new}/\g" test23
  </code></pre>