C Program to show an example of Process Management

C Program to show an example of Process Management

 #include<unistd.h>

#include<errno.h>
#include<stdio.h>
#include<stdlib.h>
int main()
{
        pid_t childpid;
        int retval;
        int status;
        childpid=fork();
        if(childpid>=0)
        {
                if(childpid==0)
                {
                        printf("CHILD : I am the child process\n");
                        printf("CHILD : Here's my PID : %d\n", getpid());
                        printf("CHILD : My parent's PID is : %d\n",getpid());
                        printf("CHILD : The value of my copy of childpid is :%d\n",childpid);
                        printf("CHILD : Sleeping for 4 seconds...\n");
                        sleep(4);
                        printf("CHILD : Enter an exit value (0 to 255): ");
                        scanf("%d",&retval);
                        printf("CHILD : Good Bye\n");
                        exit(retval);
                }
                else
                {
                        printf("PARENT : I am the parent process\n");
                        printf("PARENT : Here's my PID : %d\n", getpid());
                        printf("PARENT : The value of my copy of childpid is :%d\n",childpid);
                        printf("PARENT : I will now wait for my child to exit.\n");
                        wait(&status);
                        printf("PARENT : CHILD's exit code is : %d\n", WEXITSTATUS(status));
                        printf("PARENT : Good Bye\n");
                        exit(0);
                }
        }
        else
        {
                perror("fork");
  exit(0);
        }
}