Using workflow variables for delegate tags.
1.) Create a workflow variable for example : delegatetagname marked as Required " Yes " (see image below)
2.) Open the shell script step and in the Delegate Selectors type :
${workflow.variables.delegatetagname} (see image below)
3.) Make sure to add a tag to your delegate in the delegate page (see image below)
4.) Now when you deploy your workflow, you will need to enter the delegate tag value you want the shell script to run on. (see image below)
5.) You can validate that the shell script ran on the specific delegate you wanted it to run on (see image below) You can match the delegate name from execution of workflow to Step 3 (delegate name and tag)
Note : If you have same tag name added in multiple delegates it will randomly choose between them.