/*
 * Sample program for dup2 system call - No.63
 *
 * 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
 *     position is modified by using lseek on one of the descrip-
 *     tors, the position is also changed for the other.
 *
 *     The two descriptors do not share the close-on-exec flag,
 *     however.
 *
 *     dup uses the lowest-numbered unused descriptor for the new
 *     descriptor.
 *
 *     dup2 makes newfd be the copy of oldfd, closing newfd first
 *     if necessary.
 */

#include <stdio.h>
#include <fcntl.h>   /* for O_CREAT and O_WRONLY */
#include <stdlib.h>  /* for system() */

main()
{
	int fd;

	fd = open("foo.txt", O_CREAT | O_WRONLY, 0666);
	dup2(fd, 1);
	system("/bin/ls");
}