Assignment 1 Solution

Purpose







The goals of this assignment are the following:




Gain more experience with the C programming language from an OS perspective



Get experience with the fork(), wait(), execl(), execlp(), and pipe()system functions



Part I: Parent and Child Processes (50 points)







Write a program in C that will perform the following tasks:




Your program will create a parent process which will create two child processes (e.g., child_1, and child_2)



parent will wait for child_1 to complete before creating child_2



child_1 will create its own child child_1.1



Inside child_2, a system call to an external program will be made (let’s say this external program is “external_program.out” that prints “Hello World”), and as a result of this external program call, child_2 will be replaced by external_program.out (hint: execl())



The expected output from your program should look like the following:




parent process (PID 2255) created child_1 (PID 2256)




parent (PID 2255) is waiting for child_1 (PID 2256) to complete before creating child_2 child_1 (PID 2256) created child_1.1 (PID 2257) child_1 (PID 2256) is now completed




parent (PID 2255) created child_2 (PID 2258)




child_2 (PID 2258) is calling an external program external_program.out and leaving child_2… From the external program: Hello World..




Your submission file must be assignment1_part1.c.




Hints: fork(), wait(), getpid(), getppid(), execl()







Part II: Inter-Processes Communications (50 points)







Write a C program that will accept two integer values from the user as command line arguments (for example, X and Y). Your program will create a parent and child where the parent process will read X and the child process will read Y. Now, child process will send Y to parent process by communicating parent process through a pipe (i.e., shared memory). Then the parent process will add Y to X and produce the sum. The expected output from your program should look like the following:




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A pipe is created for communication between parent (PID 2255) and child



parent (PID 2255) created a child (PID 2256)



parent (PID 2255) Reading X = 10 from the user



child (PID 2256) Reading Y = 20 from the user



child (PID 2256) Writing Y into the pipe



parent (PID 2255) Reading Y from the pipe (Y = 20)



parent (PID 2256) adding X + Y = 30



Your submission file must be assignment1_part2.c.




Hints: fork(), wait(), getpid(), getppid(), pipe(), write(), read()




Mark Distribution







This section describes a tentative allocation of marks assigned for the desired features.




Part I: Parent and Child Processes (50 points)



A Parent process will create two Child processes: 10 points



Child_1 will create its own child Child_1.1: 10 points



Parent will wait for Child_1 to complete before creating Child_2: 10 points



Child_2 will make a system call to external_program.out: 20 points



Part II: Inter-Processes Communications (50 points)



Parent reads X from user: 5 points



Child reads Y from user: 5 points



A pipe is created for communication between Parent and Child: 15 points



Child writes Y into the pipe: 10 points



Parent reads Y from the pipe: 10 points



Parent adding two variables X+Y: 5 points






Assignment computing platform







Please visit the course website for assignment related specific technical instructions (Assignment submission, Assignment computing platform, relevant materials etc.). Also, consult TAs, and Instructor for any question you may have regarding this assignment.








































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