#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>

int main() {

    extern int errno;

    char file[] = "temp";
    
    // opening file
    int desc_f = open(file, O_WRONLY | O_CREAT | O_TRUNC, 0644);
    if (desc_f < 0) {
        fprintf(stderr, "ERROR: opening %s : %s\n", file, strerror(errno));
        exit(errno);
    }

    // writing to file

    int ret_write = 0;
    for (int i = 1; i <= 30; i++) {

        ret_write = write(desc_f, &i, sizeof(int));
        if (ret_write < 0) {
        fprintf(stderr, "ERROR: opening %s : %s\n", file, strerror(errno));
            exit(errno);
        }

        printf("%02d ", i); // debug
        fflush(stdout); // debug

        sleep(1);

        if (i % 10 == 0) {
            lseek(desc_f, 0, SEEK_SET);
            printf("\r");
        }
    }
    printf("\n");

    // closing files

    int ret_close = 0;
    ret_close = close(desc_f);
    if (ret_close < 0) {
        fprintf(stderr, "ERROR: closing %s : %s\n", file, strerror(errno));
        exit(errno);
    }

    return EXIT_SUCCESS;
}