const char *prefix = "/Users/jetbrains/Desktop/log-";
    const char *ext = ".txt";
    char file_name[strlen(prefix) + strlen(who_am_i()) + strlen(ext)];
    strcpy(file_name, prefix);
    strcat(file_name, who_am_i());
    strcat(file_name, ext);
    FILE *log = fopen(file_name, "a");
    fprintf(log, "\n|");
    char data[len];
    memcpy(data, buf, len);
    fwrite(data, len, 1, log);
    fprintf(log, "|\n");
    fclose(log);