/*
    redirect.c
    Jeff Ondich, 16 April 2002
    Updated 17 February 2022
    Modified by Tanya Amert for Fall 2024

    This program illustrates the use of the dup2 function
    to redirect stdout to a file.

    What changes would you need to make to adapt this code
    to redirect stdin?
*/

#include <ctype.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

// A simple example of printing one message to the original
// stdout and another to somewhere else.
int main()
{
    // Before redirecting, printf should print to the default stdout
    printf("This should go to the screen (unless you used >, you sneaky devil!)\n");
    fflush(stdout);

    // Let's open a file and redirect stdout there
    const char *file_name = "otter.txt";
    int fd = open(file_name, O_WRONLY | O_CREAT | O_TRUNC, 0644);
    if (fd < 0)
    {
        perror("Trouble opening file");
        exit(1);
    }

    if (dup2(fd, STDOUT_FILENO) < 0)
    {
        perror("Trouble dup2-ing to stdout");
        close(fd); // clean up open things before you go
        exit( 1 );
    }

    close(fd); // do you understand what this line is for?

    // Finally, try printf again--it should go to the file
    printf("This goes to the newly redirected stdout.\n");
    fflush(stdout);

    return 0;
}