CS 471 – Final Name__________________________
Exam must be returned to instructor by midnight, Monday, April 30
If you desire, you may fax your exam to the CS office. The number is 757-683-4900.
The exam is open book and open notes, but any work you turn in must be your own. By
submitting this work to the instructor, you are pledging that you neither gave nor
received assistance on this exam.
1. (5 pts) What is the purpose of “magic numbers” in UNIX? What does the OS error
message “bad magic number” mean? How is the same issue addressed in Windows?
2. (5 pts) In UNIX, after a fork() call, how is a child process distinguished from the parent
process? Also, why does a programmer have to worry about this issue?
3. (5 pts) UNIX keeps track of the number of links to a file. Why is this necessary?
4. (10 pts) If deadlock is controlled by the banker's algorithm, which of the following changes
can be made safely? For each explain why or why not.
a. Increase Available
b. Decrease Available
c. Increase Max for one process
d. Decrease Max for one process
e. Increase the number of processes
f. Decrease the number of processes
5. (10 pts) Which of the following programming techniques are “good” for a demand-paged
environment? Which are not good? Justify your answer.
a. Stack
b. Hashed symbol table
c. Sequential search
d. Binary search
6. (5 pts) Why does
cpp prog.cc | cc1 | cc2 | as > prog.o
present a bounded buffer problem?
7. (5 pts) How does a system administrator allow some networked machines to provide rpc,
ftp, or telnet services while keeping others from providing these same services?
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