title: Sed command failing because of / in replacement pattern
body: <p>I have this ECS task definition as follow:</p>
  
  <pre><code>{
      ...
      "image": "123.dkr.ecr.us-east-1.amazonaws.com/foo:1.0",
      ...
      "image": "123.dkr.ecr.us-east-1.amazonaws.com/bar:latest",
      ....
  }
  </code></pre>
  
  <p>I need to replace only the first "image" value, for instance:</p>
  
  <pre><code>{
      ...
      "image": "123.dkr.ecr.us-east-1.amazonaws.com/foo:2.0",
      ...
      "image": "123.dkr.ecr.us-east-1.amazonaws.com/bar:latest",
      ....
  } 
  </code></pre>
  
  <p>Here's my command <code>sed -e "s/.*foo:.*/\"image\":\"${REPO}:${VERSION}\",/" taskdef.json</code></p>
  
  <p>Where <code>REPO=123.dkr.ecr.us-east-1.amazonaws.com/foo</code> and <code>VERSION=2.0</code></p>
  
  <p>This is the error I got:</p>
  
  <pre><code>sed: -e expression #1, char 70: unknown option to `s'
  </code></pre>
  
  <p>This happens because the slash <code>/</code> from <code>REPO</code> variable. </p>