/*
 * Sample program for dup system call  - No.41
 *
 * dup, dup2 - duplicate a file descriptor
 *
 * Synopsis
 *     #include <unistd.h>
 *
 *     int dup(int oldfd);
 *     int dup2(int oldfd, int newfd);
 *
 * Description
 *     dup and dup2 create a copy of the file descriptor oldfd.
 *     After successful return of dup or dup2, the old and new
 *     descriptors may be used interchangeably. They share locks,
 *     file position pointers and flags; for example, if the file
 *     posision is modified by using lseek on one of the descriptors,
 *     the position is also changed for the other.
 *
 *     The two descriptors do not share the close-on-exec flag,
 *     however.
 */

#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>

main()
{
	int fd1, fd2;
	char *s1 = "hello, ";
	char *s2 = "world\n";
	char buf[BUFSIZ];
	FILE *fp;

	fd1 = creat("foo", S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);

	fd2 = dup(fd1); /* dup system call */

	write(fd1, s1, strlen(s1));
	write(fd2, s2, strlen(s2) + 1);

	close(fd1);

	system("cat foo");

	exit(0);
}