#include <stdio.h>
#include <stdlib.h>

// redirect stdout to a file
int
main(int ac, char *av[])
{
    int c;

    int fd = creat(av[1], 0600);
    if (fd == -1)
        perror("creat"), exit(-1);

    if (dup2(fd, 1) == -1)
        perror("dup2"), exit(-1);

    // echo stdin to stdout
    // stdout is redirected to file 'fd'
    while ((c = fgetc(stdin)) != EOF)
        fputc(c, stdout);
}