void rotate() {
    fclose(filelogs);
    char tmp[100];
    strcpy(tmp, fileName);
    int count = 0;
    while(access(tmp, F_OK) == 0) {
        count++;
        sprintf(tmp, "%s.%d", fileName, count);
    }
    for(int i = count; i > 0; i--){
        char newname[100], oldname[100];
        if(i==1){
            strcpy(oldname, fileName);
        }
        else{
            sprintf(oldname, "%s.%d", fileName, i-1);
        }
        sprintf(newname, "%s.%d", fileName, i);
        rename(oldname, newname);
    }
    filelogs = fopen(fileName, "w");
}