/*------------------------------------------------------------------*/
/* textforkexecwait.c                                               */
/* Author: Bob Dondero                                              */
/* The fork, exec, and wait system calls.                           */
/*------------------------------------------------------------------*/

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

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

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

      if (iPid == 0)
      {
         /* This code is executed by only the child process. */
         char *ppcArgv[2];

         ppcArgv[0] = "date";
         ppcArgv[1] = NULL;

         execvp(ppcArgv[0], ppcArgv);
         perror(argv[0]);
         exit(EXIT_FAILURE);
      }

      /* This code is executed by only the parent process. */

      /* Wait for the child process to finish. */
      iPid = wait(NULL);
      if (iPid == -1) {perror(argv[0]); return EXIT_FAILURE; }

      /* Pause for a while. */
      sleep(3);
   }

   /* Never should reach this point. */
}

/*------------------------------------------------------------------*/

/* Sample execution:

$ gcc -Wall -ansi -pedantic hello.c -o hello

$ gcc -Wall -ansi -pedantic testforkexecwait.c -o testforkexecwait

$ gcc -Wall -ansi -pedantic testforkexecwait.c -o testforkexecwait

$ testforkexecwait
Sat Dec  8 16:18:13 EST 2007
Sat Dec  8 16:18:16 EST 2007
Sat Dec  8 16:18:19 EST 2007
Sat Dec  8 16:18:22 EST 2007
Sat Dec  8 16:18:25 EST 2007
Ctrl-C

*/