在kaggle上创建kernel，加入如下代码。

连续运行两次，可以看到保存的文件名字不一样，且无论运行错少次，都只有一个输出文件。

这说明，kaggle上的kernel每次commit运行，都会清空输出文件。

# This Python 3 environment comes with many helpful analytics libraries installed

It is defined by the kaggle/python docker image: https://github.com/kaggle/docker-python

For example, here's several helpful packages to load in

import numpy as np # linear algebra
import pandas as pd # data processing, CSV file I/O (e.g. pd.read_csv)

df = pd.DataFrame({'name': ['Raphael', 'Donatello'],
'mask': ['red', 'purple' ],
'weapon': ['sai', 'bo staff' ]})
df.to_csv(index=False)

import time

def get_now_time_string():
return time.strftime("%Y%m%d_%H%M%S",time.localtime())

file_name = get_now_time_string() + '.csv'
df.to_csv(file_name)
print(file_name, 'saved.')