mars:$ cat modshell1.3.cpp
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <iostream.h>
#include <string>
#include <iomanip.h>
#include <sys/wait.h>

int main()
 {
  cout<<"You have entered my 1814 shell"<<endl;
//  string command;
  char line[256], *doit[20];
  int n, pid, parentpid, childpids[0];


  while (line !="exit")
      {

        cout<<"GIMME:#";
        cin.getline(line, 256);
//     cin.getline(line,sizeof(line));
        cout<<"The command you typed was: " <<line<<endl;
        doit[0] = strtok(line, " ");
        int i=1;
        while (doit[i]=strtok(NULL, " "))
            i++;
        doit[i]=NULL;

        if (strcmp(line,"exit")==0)
           return 0;

        parentpid=getpid();
        printf("I am the parent process and my pid is %d\n", getpid());
        if (pid=fork())
 {
             int status;
             waitpid(-1, &status, 0);
             childpids[n]=pid;
          }
                  else
          {
             printf("I am a child process and my pid is %d\n", getpid());
             cout<<"Parameters are: "<<endl;
              for (int j=0; j<i; j++)
                  cout<<doit[j]<<endl;
             cout<<"       EXECUTE CHILD"<<endl;
             execve(doit[0], doit, NULL);
             exit(0);
          }
       cout<<"     KILL CHILD AND RETURN TO PARENT"<<endl;
       printf("I am still the parent process and my pid is %d\n",
         getpid());
   }//end of while
 if (line =="exit")
 return 0;

printf("I am still the parent process and my pid is %d\n", getpid());
}//end of main