删除文件的前N行 [英] Remove first N lines of file

问题描述

我想知道如何高效地删除特定文件的前N行.

I was wondering how I can remove the first N lines of a specific file efficiently.

当然，我们可以将完整的文件加载到内存中，然后删除前N行并将完整的更改内容写入文件.

Of course, we can load the complete file into memory, then remove the first N lines and write the complete changed contents to the file.

但是，我想知道是否有办法比仅将所有内容加载到内存中更有效.

But, I was wondering if there is a way to make this more effective compared to just loading all contents in memory.

推荐答案

文件系统不支持从文件的任意位置删除，因此您至少需要自己重新编写整个文件.实施所需内容的常用方法是

Filesystems doesn't support deleting from arbitrary locations of a file, so you at least need to re-write the entire file yourself. The common way to implement what you need is to

• 打开一个临时文件，
• 从原始文件中读取小片段，例如在您的情况下，每次只能一行一行
• 仅将要保留在原始文件中的行写到临时文件中
• 完成后，将临时文件重命名为原始文件名.

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