#include <iostream>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>

using namespace std;

int main() {
    int fd, fd2, dupedFD;
    int i;
    char buf[]="This is a test writing to stdout from another file descriptor\n";

    fd = open("duptest", O_WRONLY | O_CREAT, S_IRUSR| S_IWUSR|S_IRWXG|S_IRWXO);
    fd2 = open("duptest", O_WRONLY | O_CREAT, S_IRUSR| S_IWUSR|S_IRWXG|S_IRWXO);

    cout << "The first file descriptor I opened was " << fd << endl;
    cout << "The second file descriptor I opened was " << fd2 << endl;

    dupedFD = dup(fd);

    cout << "I duped a new one, it is " << dupedFD << endl;

    for(i = 0; i < 10; i++) {
        if (i%2) {
	    write(fd,&i, sizeof(int));
	} else {
	    write(dupedFD,&i, sizeof(int));
	}
    }
    cout << " file  descriptor " << fd << " is at position "
         << lseek(fd, 0, SEEK_CUR) << endl;
    cout << " file  descriptor " << dupedFD << " is at position " 
         << lseek(dupedFD, 0, SEEK_CUR) << endl;
    // this is a different entry in the file table, even though it was opened
    // with the same command.
    cout << " file  descriptor " << fd2 << " is at position "
         << lseek(fd2, 0, SEEK_CUR) << endl;
 
    // but move to the end of fd2

    cout << "After seeking to the end of " << fd2 << endl;
    lseek(fd2, 0,SEEK_END);
    cout << " file  descriptor " << fd2 << " is at position "
         << lseek(fd2, 0, SEEK_CUR) << endl;

    close(fd);
    close (dupedFD);

    fd = dup(STDOUT_FILENO);

    write(fd, buf, strlen(buf));


    return 0;
}