当您对与 dup2() 复制的管道文件描述符调用 close() 时会发生什么？

Question

I have a question regarding file descriptors in Unix and C programming.

Let's say I use pipe(fd) to get file descriptor 3 and 4 for the pipe ends, 3 connects to the read end and 4 to the write end.

Now I use dup2(fd[write_end],1) to copy the descriptor of the write end (which was 4) to file descriptor 1 in my process. If I now do close(fd[write_end]) will it close descriptor 1 or descriptor 4?

Answer 1

After a successful call to dup2 , both file descriptors are valid.

When you then call close(fd[write_end]) , because fd[write_end] is set to 4 this is the same as close(4) . So file descriptor 1 remains open and usable.