8.5. Coroutines

We've spent the last several pages on almost microscopic details of process behavior. Rather than continue our descent into the murky depths, we'll revert to a higher-level view of processes.

Earlier in this chapter, we covered ways of controlling multiple simultaneous jobs within an interactive login session; now we'll consider multiple process control within shell programs. When two (or more) processes are explicitly programmed to run simultaneously and possibly communicate with each other, we call them coroutines.