linux为什么不能对目录建立硬链接？

Question

linux文件系统中，为什么不能对目录建立硬链接？

Answer 1

http://askubuntu.com/questions/210741/why-are-hard-links-not-allowed-for-directories

; Generally, it is currently impossible to use hard links for directories. Once used, messages such as operation
; not permitted will appear.
;
; Directories are not allowed to use hard links. The reason is generally that hard links are required in directories
; If used, it means that all files and subdirectories in the directory must be processed. Hard link action,
; The result level has been separated from the hard link situation of simple general file projects.
;
; Next, once hard link is allowed in the directory, if you create a file
; and directory in the directory, this means that the files in these two directories must be processed as hard link situation, then the entire
; environment will become very complicated.

http://bbs.chinaunix.net/thread-2212171-1-1.html

Answer 2

http://unix.stackexchange.com/questions/22394/why-are-hard-links-to-directories-not-allowed-in-unix-linux

Answer 3

You have to post the error message, it may be a permissions issue

Answer 4

Because after you ln . xxx, then rm -rf xxx will enter the D state.