#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <assert.h>
#include <fcntl.h>
#include <sys/wait.h>
#include <sys/types.h>

int main(int argc, char *argv[])
{
    if (argc < 2)
    {
        printf("Usage: %s <file>\n", argv[0]);
        return EXIT_FAILURE;
    }

    int pip, fd[2], outfile, d;
    char buf;
    pip = pipe(fd);
    assert(pip != -1);

    pid_t p = fork();
    assert(p != -1);

    outfile = open(argv[1], O_WRONLY | O_CREAT, 0644);

    switch (p)
    {
    case 0:
        close(fd[0]);
        d = dup2(fd[1], 1);
        execl("/usr/bin/ls", "ls", "-i", "-l", "/tmp", NULL);
        close(fd[1]);
        exit(0);
    default:
        close(fd[1]);
        while (read(fd[0], &buf, sizeof(char)) > 0)
        {
            write(outfile, &buf, sizeof(char));
        }
        break;
    }

    close(outfile);
    return EXIT_SUCCESS;
}