In the preceding chapters, we have described how a general purpose operating system can be constructed. At present our operating system exists somewhat in a vacuum, since we have not yet specified how we can inform it about the jobs that we want it to do. The next step is to manufacture an interface between the user and the operating system so that the user can tell the system what is required of it. The interface can also be used to present information, such as resource requirements, about each job so that the system can optimise performance in the ways described earlier. Of course, communication between user and system is not all in one direction; we must also construct a complementary interface through which the system can tell the user what it has been doing.
KeywordsControl Card Command Language Schedule Information Preceding Chapter UNIX Shell
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