Comp307 LAB 1-Understanding Process Concepts Solved

LAB-1 (Understanding Process Concepts)

1. Write a C program to implement process System calls ? [Hint use fork())]
2. How many processes are created in a given program? #include <stdio.h>

   #include <unistd.h> int main()
   {
   int i;

   for (i = 0; i < 4; i++) fork();
   return 0;
   }

3. When will line J be reached? #include <sys/types.h>

   #include <stdio.h> #include <unistd.h> int main()
   {

   pid_t pid;
   /* fork a child process */
   pid = fork();
   if (pid < 0) { /* error occurred */ fprintf(stderr, “Fork Failed”);
   return 1;
   }
   else if (pid == 0) { /* child process */ execlp(“/bin/ls”,”ls”,NULL);
   printf(“LINE J”);
   }
   else { /* parent process */
   /* parent will wait for the child to complete */ wait(NULL);
   printf(“Child Complete”);
   }
   return 0;
   }

4. What are the pid values?
   #include <sys/types.h>

   #include <stdio.h> #include <unistd.h> int main()
   {

   pid_t pid, pid1;
   /* fork a child process */
   pid = fork();
   if (pid < 0) { /* error occurred */ fprintf(stderr, “Fork Failed”);
   return 1;
   }
   else if (pid == 0) { /* child process */ pid1 = getpid();
   printf(“child: pid = %d”,pid); /* A */ printf(“child: pid1 = %d”,pid1); /* B */
   }
   else { /* parent process */
   pid1 = getpid();
   printf(“parent: pid = %d”,pid); /* C */ printf(“parent: pid1 = %d”,pid1); /* D */ wait(NULL);
   }
   return 0;
   }

5. What will be at Line X and Line Y?

   #include <sys/types.h> #include <stdio.h> #include <unistd.h> #define SIZE 5

   int nums[SIZE] = {0,1,2,3,4}; int main()
   {
   int i;

   pid t pid;
   pid = fork();
   if (pid == 0) {
   for (i = 0; i < SIZE; i++) {
   nums[i] *= -i;
   printf(“CHILD: %d “,nums[i]); /* LINE X */

}
}
else if (pid > 0) {
wait(NULL);
for (i = 0; i < SIZE; i++)
printf(“PARENT: %d “,nums[i]); /* LINE Y */ }
return 0;
}