Question

1. Write program codes for 3.21 a and shared memory program b for producer and consumer as shown in the following. You can start with the code provided in the virtual machine in the virtual box you installed. The code can be found in /home/oscreader/osc9e-src/ch3 a. For 3.21, you can start with the newproc-posix.c and modify the code to meet your requirement. Then type: gcc newproc-posix.c to compile, then type. /a.out to execute

Source code to modify:

#include <stdio.h>

#include <unistd.h>

#include <sys/types.h>

int main()

{

pid_t pid;

/*fork a child process*/

pid = fork();

if (pid<0){ /*error occured*/

fprintf(stderr,"Fork failed\n");

return 1;

}

else if (pid == 0) { /*child process */

printf("I am the child %d\n",pid);

execlp("/bin/ls","ls",NULL);

}

else { /*parent process */

/*parent will wait for the child to complete*/

printf("I am the parent %d\n",pid);

wait(NULL);

printf("Child Complete\n");

}

return 0;

}

Answer 1

//Working Code :-

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
int n=35;
int main(){
pid_t pid;
pid = fork();
if (pid<0){ 
fprintf(stderr,"Fork failed\n");
return 1;
}
else if (pid == 0) { 
    execv("child",NULL);
printf("Now executing child \n ");
while(1){
    printf("%d ",n);
    if(n==1)
    break;
    else
    {
        if(n%2==0)
        n=n/2;
        else
        n = (3*n)+1;
    }
}
printf("\n");
exit(1);
}
else { 
printf("first execution by parent class \n");
wait();
printf("Child Complete\n");}
return 0;
}

//Output ;-

/tmp/6KSqV79rez.o first execution by parent class Now executing child 35 106 53 160 80 40 20 10 5 16 8 4 2 1 Child Complete #include <stdio.h> #include <unistd.h> #include <sys/types.h> int n=35; int main({ pid_t pid; pid = fork; if (pid=0){ | fprintf(stderr, "Fork failed\n"); return 1; } else if (pid == 0) { execv("child",NULL); printf("Now executing child \n "); while(1) { printf("%d ",n); if(n==1) break; else { if(n%2==0) n=n/2; else n = (3*n)+1; } } printf("\n"); exit(1); } else { printf("first execution by parent class \n"); wait(); printf("Child Complete\n");}

//Comments :- keep parent process in wait() state till child process get complete , child process notifies with exit(1) code that it is done then parent process will continue , and also in above code while(1) is written , insense think contrary to above collatz conjecture, if its false then it the code should run infinite times , but when you run you will see it runs for definite time and stope when n value is 1, for simplicity n is predeclared as global variable can change if one wants to