Subject: Re: bug#19051: rm symboliclink/ # "Is a directory"

From: Eric Blake <[email-masked]>
Date: Fri, 14 Nov 2014 07:47:44 -0700

On 11/14/2014 06:15 AM, Eric Blake wrote:

>> Confused me too when I encountered it first, but tt's required by POSIX:
>> http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap04.html#tag_04_11
> 
> No, actually, POSIX requires that it (attempt to) remove the DIRECTORY,
> not the symlink.  Linux is intentionally in violation of POSIX on this
> front.
> 
> Try this on Solaris:
> 
> $ mkdir a
> $ ln -s a b
> $ rm b/
> $ ls -d ?
> b

Uggh, serves me right for typing without testing.  I'm mixing up
rename(), unlink(), and rmdir() semantics.  Basically,
unlink("anything/") is required by POSIX to fail because the trailing /
means that the only thing to be removed is a directory, but directories
can only be removed by rmdir(), not unlink().

Still, my point remains when you use 'rm -r b/': on Linux, it fails
(cannot remove 'b/': Not a directory), on Solaris it succeeds at
removing 'a' and leaving 'b' dangling.

The fact that Linux intentionally violates POSIX on some of the corner
cases related to symlinks to directories makes it harder to definitively
state what coreutils should do.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org