CentOS - Sep 2018 - Very weird problem with handling symbolic links

Hi everyone,

I just discovered something very weird on a vanilla CentOS 7
installation. If I create a link to /tmp as a normal user, it looks like
I can't remove this link anymore. Here's what this looks like:

  $ mkdir test_link
  $ cd test_link/
  $ ln -s /tmp/ link_to_tmp
  $ ls -l
  total 0
  lrwxrwxrwx. 1 kikinovak kikinovak 5 Sep 17 10:56 link_to_tmp -> /tmp/
  $ rm link_to_tmp/
  rm: cannot remove ?link_to_tmp/?: Is a directory
  $ rmdir link_to_tmp/
  rmdir: failed to remove ?link_to_tmp/?: Not a directory

I tried the same thing on a different box, running Slackware 14.2, and I
can remove my symbolic link without any hassle.

I sense something is very wrong here. Any suggestions?

Niki
-- 
Microlinux - Solutions informatiques durables
7, place de l'?glise - 30730 Montpezat
Site : https://www.microlinux.fr
Blog : https://blog.microlinux.fr
Mail : info at microlinux.fr
T?l. : 04 66 63 10 32

Le 17/09/2018 ? 11:05, Nicolas Kovacs a ?crit?:
>   $ mkdir test_link
>   $ cd test_link/
>   $ ln -s /tmp/ link_to_tmp
>   $ ls -l
>   total 0
>   lrwxrwxrwx. 1 kikinovak kikinovak 5 Sep 17 10:56 link_to_tmp -> /tmp/
>   $ rm link_to_tmp/
>   rm: cannot remove ?link_to_tmp/?: Is a directory
>   $ rmdir link_to_tmp/
>   rmdir: failed to remove ?link_to_tmp/?: Not a directory
I'll answer that myself, since I just found the culprit. The trailing
slash in `link_to_tmp/` caused the problem.

  $ rm link_to_tmp <-- works perfectly

This must be one of those rare occasions where tab completion does *not*
come in handy.

Cheers,

Niki

-- 
Microlinux - Solutions informatiques durables
7, place de l'?glise - 30730 Montpezat
Site : https://www.microlinux.fr
Blog : https://blog.microlinux.fr
Mail : info at microlinux.fr
T?l. : 04 66 63 10 32

> 
>   $ mkdir test_link
>   $ cd test_link/
>   $ ln -s /tmp/ link_to_tmp
>   $ ls -l
>   total 0
>   lrwxrwxrwx. 1 kikinovak kikinovak 5 Sep 17 10:56 link_to_tmp -> /tmp/
>   $ rm link_to_tmp/
>   rm: cannot remove ?link_to_tmp/?: Is a directory
>   $ rmdir link_to_tmp/
>   rmdir: failed to remove ?link_to_tmp/?: Not a directory
> 
> I tried the same thing on a different box, running Slackware 14.2, and I
> can remove my symbolic link without any hassle.
> 
> I sense something is very wrong here. Any suggestions?
> 
Yeah, it's just one of the oddities of symlinks.  Try doing the rm
command without the trailing slash.  A symlink isn't a directory, it's
an entry that links to a directory - but if you put the trailing slash,
rm thinks it is a directory so won't touch it. I think it depends on at
what stage the symlink is dereferenced in the rm command.  Presumably
the rmdir command checks the filetype before doing anything.

I came across this when using tab completion - that puts the extra
slash on the end when encountering a directory and it caused me to go
looking for the answer.

P.