Description

Computer Engineering Department

BLG 312E – Computer Operating Systems
Homework 1

This homework is for your own practice; it will not be submitted to ninova, and it will not be graded. Note that the first quiz will be based on what you learn in this homework.

Answer below questions and explain your answers in detail.

1. Compile and run prog1.c. Write down your comments about the order of the messages printed on the screen. Include your comments about the process IDs you encounter.

2. Modify prog1.c code in order to make the parent process print the process id of its own parent. Compile and run the modified program. Write down your comments about the process id of the parent’s parent process.

3. Delete the wait(NULL) line in prog1. Compile and run the modified program. Write down your comments about the process id that child process print outs about its parent process.

4. Define a global integer variable at the beginning of prog1.c and assign a value to this variable before invoking the fork system call. Print out the value of this variable in both child and parent processes. Then, in the child and the parent processes, separately, assign different values to this variable. Afterwards, print out the value of this variable in both child and parent processes. Write down your comments about all of the values you have observed printed on the screen.

5. Define a pointer to a global integer variable at the beginning of prog1.c and allocate space for this pointer. Assign a value to this variable before the fork system call and print out both the value of the pointer (address information) and the value stored in the place where pointer is referencing. Then, in the child and the parent processes, separately, assign different values to the integer space where the pointer references. In both child and parent processes, print out the value of pointers and the integers they are referencing to. Write down your comments about all of the values you have observed (for pointer values and the values corresponding to the integers they are referencing) printed on the screen.

6. Compile and run p1.c and p2.c. Write down your comments about the outputs (printed messages on stdout) of both programs.