title: Json object not escaped properly in bash
body: <p>This is my script</p>
  
  <pre><code>#!/bin/bash
  set -x
  USERNAME="someUser"
  curl -H "Content-Type: application/json" -X POST -d '{"auth":{ "client": $USERNAME, "password": "somePassword" }, "messages": { "UpdateProduct": {} }}' http://someDomain.com/services/json
  </code></pre>
  
  <p>it just becomes as below, it did not replace <code>$USERNAME</code> with <code>someUser</code></p>
  
  <pre><code>curl -H "Content-Type: application/json" -X POST -d '{"auth":{ "client": $USERNAME, "password": "somePassword" }, "messages": { "UpdateProduct": {} }}' http://someDomain.com/services/json
  </code></pre>
  
  <p>but if i put USERNAME in, it works</p>
  
  <pre><code>curl -H "Content-Type: application/json" -X POST -d '{"auth":{ "client": "someUser", "password": "somePassword" }, "messages": { "UpdateProduct": {} }}' http://someDomain.com/services/json
  </code></pre>