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/ [/tmp/a/]$ # ???So Why this time it chooses to refer to the absolute path to determine the parent dir?
All the above operations are tested on CentOS 7.9