The contradiction here is how symlink deal with directory ../ in 2 ways:
- treat the current path as the result printed by
pwd - treat the current path as absolute path
I will discuss them with an example (pretty easy to understand).
Considering the following directory hierarchy:
/tmp/
|__a/
| |__b/
|
|__sb=./a/b/ -> /tmp/a/b/ # the name `sb' means symbol b;
# `sb' is generated by:
# [/tmp/]$ ln -s ./a/b/ sb
-
_
[/tmp/]$ cd sb # `pwd' says we are now in /tmp/ # let's change to /tmp/a/b/ [/tmp/sb/]$ cd ../ # Now we are in /tmp/a/b/ # But what is /tmp/a/b/'s parent dir? [/tmp/]$ # See? We didn't come back to /tmp/a/ BUT /tmp/It means that the current parent dir is the second from the right printed by
pwd. -
Let’s add a symlink into dir
/tmp/a/b/:/tmp/ |__a/ | |__b/ | |__sa=../ -> /tmp/a/ # [/tmp/a/b/]$ ln -s ../ sa | |__sb=./a/b/ -> /tmp/a/b/This time, we will come back to the actual parent dir of
/tmp/a/b/:[/tmp/]$ cd sb # change to /tmp/a/b/ [/tmp/sb/]$ cd sa # sa=../ # /tmp/sb/=/tmp/a/b/ # ^ or ^ [/tmp/sb/sa/]$ ls --classify b/ # ??? # We are now in /tmp/a/ because there is a b/ here!So Why this time it chooses to refer to the absolute path to determine the parent dir?
The contradiction arises when it comes to ../, but I suspect the same thing happens when it comes to relative path.
All the above operations are tested on CentOS 7.9