PART 1:
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Create a set of 4 stand‐alone programs, as follows:
Program #0 ‐ Will always be called first and must create a set of semaphores. Program #0 must print the exact text "Executing process #0." when it runs. It must then terminate.
Program #1 ‐ Will be started sometime after program #0 and must adjust the semaphore(s) such that program #2 can run. Program #1 must print the exact text "Executing process #1." when it runs. It must then terminate. Program #1 doesn't do anything else.
Program #2 ‐ Will be started sometime after program #0 and must adjust the semaphore(s) such that program #3 can run. Program #2 must print the exact text "Executing process #2." when it runs.
It must then terminate. Program #2 doesn't do anything else. However, program #2 can only run AFTER program #1 runs! If program #2 runs before program #1 it must simply terminate itself.
Program #3 ‐ Will be started sometime after program #0 and should remove the semaphores from the system. Program #3 must print the exact text "Executing process #3." when it runs. It must then terminate. Program #3 doesn't do anything else. However, program #3 can only run AFTER program #2 runs! If program #3 runs before program #2 it must simply terminate itself.
PART 2:
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We will test your code using my program (a script) that will always call program #0 first, but will call the remaining programs in all possible permutations. Obviously, to get full credit only the correct permutation should result in the following output:
Executing process #0.
Executing process #1.
Executing process #2.
Executing process #3.
SUGGESTIONS:
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See man pages for semget, semop, and semctl.
See man pages for errno and include errno.h ‐ this will make things much easier! You can use errno to troubleshoot your code and to help determine how to tell when a process is attempted out‐of‐turn.
See my web site for a new file (errno.txt).
REQUIREMENTS:
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Your program must run in Streibel 109.
Your full name must appear as a comment at the beginning of your program.
Your source code must be named hw6‐yourname.c or hw6‐yourname.cpp
Email your source (subject hw6‐yourname) to rmarsh@cs.und.edu
