Programming

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

int main(void)
{
    pid_t pid;
    int rv;

    switch(pid = fork()) {
    case -1:
        perror("fork");  /* something went wrong */
        exit(1);         /* parent exits */

    case 0:
        printf(" CHILD: This is the child process!\n");
        printf(" CHILD: My PID is %d\n", getpid());
        printf(" CHILD: My parent's PID is %d\n", getppid());
    printf(" CHILD: I am sleeping for 15 seconds\n");
        sleep(15);           // exits as a second
    printf(" CHILD: Sleeping is over\n");
    


    default:
        printf("PARENT: This is the parent process!\n");
        printf("PARENT: My PID is %d\n", getpid());
        printf("PARENT: My child's PID is %d\n", pid);
    printf("PARENT: I am sleeping for 10 seconds\n");
        sleep(10);             // exits first
    printf("PARENT: Sleeping is over\n");
    }

    return 0;
}

bash-3.2$ ./a2.out
PARENT: This is the parent process!
 CHILD: This is the child process!
PARENT: My PID is 15852
PARENT: My child's PID is 15853
PARENT: I am sleeping for 10 seconds
 CHILD: My PID is 15853
 CHILD: My parent's PID is 15852
 CHILD: I am sleeping for 15 seconds
PARENT: Sleeping is over
bash-3.2$  CHILD: Sleeping is over
PARENT: This is the parent process!
PARENT: My PID is 15853
PARENT: My child's PID is 0
PARENT: I am sleeping for 10 seconds
PARENT: Sleeping is over