How does one write an Upstart task that is guaranteed to run only once after each startup but is also guaranteed to run to completion before either one of at least two other jobs start running. I do not want to alter the Upstart init files for those two other jobs as they do not belong to me. Restarting either of those two other jobs should not cause the desired task to run again.
The situation is that the desired task must make some modifications to some files in the local filesystem that both of the other jobs will be needing.
I'm completely new to Upstart and finding it a steeper learning curve than I'd expected, so an education on why the solution works will be as valuable as the solution itself.