/*-------------------------------------------------------------------*/
/* testdupforkexec.c                                                 */
/* The dup, fork, and exec system calls.                             */
/*-------------------------------------------------------------------*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <wait.h>

int main(int argc, char *argv[])
{
   int iPid;

   printf("Parent process (%ld)\n", (long)getpid());

   fflush(NULL);
   iPid = fork();
   if (iPid == -1) {perror(argv[0]); return 1; }

   if (iPid == 0)
   {
      char *ppcArgv[2];
      int iFd;
      int iRet;

      iFd = creat("tempfile", 0600);
      if (iFd == -1) {perror(argv[0]); exit(1); }

      iRet = close(1);
      if (iRet == -1) {perror(argv[0]); exit(1); }

      iRet = dup(iFd);
      if (iRet == -1) {perror(argv[0]); exit(1); }

      iRet = close(iFd);
      if (iRet == -1) {perror(argv[0]); exit(1); }

      ppcArgv[0] = "date";
      ppcArgv[1] = NULL;
      execvp(ppcArgv[0], ppcArgv);
      perror(argv[0]);
      exit(1);
   }
   
   wait(NULL);

   /* This code is executed by only the parent process. */
   printf("Parent process (%ld)\n", (long)getpid());
   
   return 0;
}


/* Sample execution:

$ gcc -Wall -ansi -pedantic -o testdupforkexec testdupforkexec.c 
$ testdupforkexec
Parent process (25408)
Parent process (25408)
$ cat tempfile
Sun Apr 25 18:49:31 EDT 2004
$ 

*/