Run 'N' Number of PHP Scripts on shell forever in a loop
I think more than even a code review, what you are really needing to think about is your architecture.  In the modern age of event-based workflows and parallel computing should you really be managing and executing a complex set of scripts in this manner (i.e. via shell automation)?

My advice is to look for better tooling that will allow you to orchestrate your pieces of logic via an automated workflow of some sort.  Even consider things like map reduce tools (Hadoop, Elastic Map Reduce, etc.) which are ideal for parallel workload execution with aggregation of results.