title: Can not change Jenkins String Parameter Variable
body: <p>I have Jenkins String Parameter ${EMAIL_ID} where user can enter their email id. (say they entered <code>myid@gmai.com</code></p>
  
  <p>But in the middle of the process i would like to change it to some value that i specify in the configuration as below in <code>Execute Shell</code> .</p>
  
  <pre><code>EMAIL_ID='example@ex.com'
  echo $EMAIL_ID
  --returns example@ex.com
  </code></pre>
  
  <p>If I use this variable in next <code>Execute Shell</code> 
  it returns <code>myid@gmai.com</code></p>
  
  <p>I need to print <code>example@ex.com</code></p>