/*-------------------------------------------------------------------*/
/* textforkexecwait.c                                                */
/* The fork, exec, and wait system calls.                            */
/*-------------------------------------------------------------------*/

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <wait.h>

#define MAX_COMMAND_SIZE 1024

int main(int argc, char *argv[])
{
   int iPid;
   int iWaitPid;
   int iStatus;
   char pcCommandName[MAX_COMMAND_SIZE];

   printf("Enter a command (no arguments, exit to stop):  ");
   scanf("%s", pcCommandName);
   while (strcmp(pcCommandName, "exit") != 0)
   {
      iPid = fork();

      if (iPid == -1)
      {
         printf("Failed to execute fork.\n");
         exit(1);
      }

      if (iPid == 0)
      {
         char *ppcArgv[2];
         ppcArgv[0] = pcCommandName;
         ppcArgv[1] = NULL;
         execvp(ppcArgv[0], ppcArgv);
         printf("Failed to execute execvp.\n");  /* Should never reach. */
         exit(1);                                /* Should never reach. */
      }

      /* Wait for the child process to finish. */
      wait(&iStatus);
      printf("Command executed with status %d.\n\n", WEXITSTATUS(iStatus));

      printf("Enter a command (no arguments, exit to stop):  ");
      scanf("%s", pcCommandName);
   }

   return 0;
}

/* Sample execution:

$ testforkexecwait
Enter a command (no arguments, exit to stop):  hello
Hello world.
Command executed with status 0.

Enter a command (no arguments, exit to stop):  date
Sun Dec  9 21:15:41 EST 2001
Command executed with status 0.

Enter a command (no arguments, exit to stop):  exit
$

*/