You could capture the http interaction of running your activity using a tool like JMeter, and then use wget or curl in your shell script to perform the http interactions. I have not done this myself, but I use a similar approach to for other tasks.
I think Richard's suggestion would definitely work. You can also schedule an agent to call an activity at a set time from inside the system, no script required. That might be an easier solution to the problem.
Thanks. Unfortunately we can't kick off at a specific time but are tied to dependancies on a wider batch of jobs in external systems that don't necessarily run and complete at set times. We no longer have the requirment for shellscript triggering and can stick with our current JMS trigger.
Thanks for the suggestion. At the minute it looks like we will be able to stick with our current solution of triggering on receipt of a JMs message but if we have to revisit the shellscript option will give what you suggest a shot.