linux - How to copy the file description when forking instead of sharing?

Question

When a process forks, the child will share with its parent the file description that was open before the forking.

Is there a way to make the child have its own copy of the file description (that includes the offset and the file status flag)?

I need that since I don't want both parent and child to share the same offset of the file; if one process has done a read, I don't want the offset of the file for the second process to be changed.

Answer 1

既有“打开文件描述符”又有“打开文件描述”。使用 打开文件时open()，会同时创建文件描述符和文件描述。当一个文件描述符被复制（dup()或dup2()）时，这两个描述符引用相同的打开文件描述。

上fork()，父级中的文件描述符被复制（复制）到子级中；parent 和 child 中的描述符都指向相同的打开文件描述。

子进程应拥有自己的父文件描述符副本。每个子文件描述符都应与父文件描述符对应的打开文件描述相同。

否则没有办法让它工作——您必须关闭并重新打开文件才能获得单独的打开文件描述。