/*--------------------------------------------------------------------*/
/* testforkwaitpid.c                                                  */
/* Author: Iasonas Petras                                             */
/*--------------------------------------------------------------------*/

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

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

/* Demonstrate the system-level fork() and waitpid() functions.
   Return 0.
   As usual, argc is the command-line argument count, and argv
   contains the command-line arguments. */

int main(int argc, char *argv[])
{
   pid_t iPid;
   int iRet;
   int i = 0;
   int iStatus;

   printf("%d parent\n", (int)getpid());

   iRet = fflush(NULL);
   if (iRet == EOF) {perror(argv[0]); exit(EXIT_FAILURE); }

   iPid = fork();
   if (iPid == -1) {perror(argv[0]); exit(EXIT_FAILURE); }

   if (iPid == 0)
   {
      /* This code is executed by the child process only. */
      for (i = 0; i < 10; i++)
         printf("%d child %d\n", (int)getpid(), i);
      exit(0);
   }

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

   /* Wait for the child process to terminate. */
   iPid = waitpid(iPid, &iStatus, 0);
   if (iPid == -1) {perror(argv[0]); exit(EXIT_FAILURE); }

   if (WIFEXITED(iStatus))
      printf("Child with process id %d exited with status=%d\n", iPid,
             WEXITSTATUS(iStatus));
   
   for (i = 0; i < 10; i++)
      printf("%d parent %d\n", (int)getpid(), i);

   return 0;
}

/*

$ gcc217 testforkwaitpid.c -o testforkwaitpid

$ ./testforkwaitpid
22859 parent
22860 child 0
22860 child 1
22860 child 2
22860 child 3
22860 child 4
22860 child 5
22860 child 6
22860 child 7
22860 child 8
22860 child 9
Child with process id 22860 exited with status=0
22859 parent 0
22859 parent 1
22859 parent 2
22859 parent 3
22859 parent 4
22859 parent 5
22859 parent 6
22859 parent 7
22859 parent 8
22859 parent 9

*/