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Asynchronous Execution
It is sometimes desirable to perform more than one task at the same time. We have seen how all modern operating systems are at least multitasking if not multiuser as well. Scripts can be constructed to behave in a multitasking fashion.
Usually this involves launching a script that, in turn, launches one or more child scripts that perform an additional task while the parent script continues to run. However, when a series of scripts runs this way, there can be problems keeping the parent and child coordi- nated. That is, what if the parent or child is dependent on the other, and one script must wait for the other to finish its task before finishing its own?
bash has a builtin command to help manage asynchronous execution such as this. The wait command causes a parent script to pause until a specified process (i.e., the child script) finishes.