在python中创建特定大小的文件 [英] create file of particular size in python

问题描述

我想创建一个特定大小的文件(例如1GiB). 内容并不重要，因为我会在其中填充内容.

I want to create a file of particular size (say, 1GiB). The content is not important since I will fill stuff into it.

我正在做的是:

f = open("E:\\sample", "wb")
size = 1073741824 # bytes in 1 GiB
f.write("\0" * size)

但这需要很长时间才能完成.我花了大约1分钟的时间. 可以做些什么来改善这一点?

But this takes too long to finish. It spends me roughly 1 minute. What can be done to improve this?

推荐答案

警告该解决方案提供的结果可能出乎您的意料.参见UPD ...

WARNING This solution gives the result that you might not expect. See UPD ...

1创建新文件.

2尝试将大小限制为1个字节.

2 seek to size-1 byte.

3写1个字节.

4利润:)

f = open('newfile',"wb")
f.seek(1073741824-1)
f.write(b"\0")
f.close()
import os
os.stat("newfile").st_size

1073741824

UPD: 在我的系统(Linux + ReiserFS)上查找和截断这两个都将创建稀疏文件.它们具有所需的大小，但实际上不占用存储设备上的空间.因此，这不是快速分配空间的正确解决方案.我刚刚创建了100Gib文件，该文件只有25Gib可用，但结果仍然有25Gib可用.

UPD: Seek and truncate both create sparse files on my system (Linux + ReiserFS). They have size as needed but don't consume space on storage device in fact. So this can not be proper solution for fast space allocation. I have just created 100Gib file having only 25Gib free and still have 25Gib free in result.

次要更新: 为了与Py3兼容，在f.write("\0")中添加了b前缀.

Minor Update: Added b prefix to f.write("\0") for Py3 compatibility.

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