x
int dup(int oldfd);
int dup2(int oldfd, int newfd);
/* See feature_test_macros(7) */
/* Obtain O_* constant definitions */
int dup3(int oldfd, int newfd, int flags);
xxxxxxxxxx
int main() {
int fd, save_fd;
if ((fd = open("test.txt", O_RDWR)) < 0) {
perror("open");
exit(1);
}
save_fd = dup(1);
write(1, "hello stdout\n", 13);
dup2(fd, 1);
close(fd);
write(1, "hello test.txt\n", 15);
dup2(save_fd, 1);
close(save_fd);
return 0;
}