CODEWITHSUNDEEP
clinuxprocesslinux-kernelfork
john
john

Reputation: 1383

forking a process and waiting for child to exit

Iam programing in C language and trying to learn the concepts of forking a process , bt iam getting confused with the output of the following program. So i need some explanation regarding this to proceed. 

        int main() {
            pid_t pid;
 24         int status, died;
 25         switch(pid = fork()){
 26                 case -1: printf("Can't fork\n");
 27                          exit(-1);
 28                 
 29                 case 0 : printf(" Child is sleeping ...\n"); 
 30                          sleep(5); // this is the code the child runs
 31                          //exit(3); 
 32                          
 33                 default:
 34                          printf("Process : parent is waiting for child to exit\n");
 35                          died = wait(&status); // this is the code the parent runs 
 36                          printf("Child's process table cleared...\n");
 37         }
 38         return 0;
 39 }

The output of the above program is :

Process : parent is waiting for child to exit
Child is sleeping ...
Process : parent is waiting for child to exit
Child's process table cleared...
Child's process table cleared...

Here iam not getting why this "Child's process table cleared..." is coming twice. Pls explain.

Platform : Linux , gcc compiler

Upvotes: 0

Views: 304

Answers (2)

john
john

Reputation: 1383

i got it what i was missing ... it is because of the absence of the break statement there.If i would have used break or exit(), output wouldn't have been like this. Thanks.

Upvotes: 0

Pavan Manjunath
Pavan Manjunath

Reputation: 28525

There is no break in the child's case statement and hence the child too executes the default statement

You seem to have commented out exit(3). It would have been better if it were there.

Upvotes: 6

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