Subject: Re: bug#24730: rmdir/mkdir error(s) and/or not working "reciprocally" w/each other
From: Eric Blake <[email-masked]>
To: "L. A. Walsh" <[email-masked]>, [email-masked]
Date: Tue, 18 Oct 2016 15:33:43 -0500
List-Id: <debbugs-submit.debbugs.gnu.org>

tag 24730 notabug
thanks

On 10/18/2016 02:49 PM, L. A. Walsh wrote:
> 
> It doesn't seem rmdir and mkdir are behaving "reciprocally"...
> 
> If I type
> 
> mkdir -p ./a/b/c   # no error

. already exists, so mkdir silently does nothing,
./a needs to be created,
./a/b needs to be created,
./a/b/c needs to be created

> rmdir -p ./a/b/c   # get error msg, but a,b,c removed.

./a/b/c needs to be removed,
./a/b needs to be removed,
./a needs to be removed,
. needs to be removed, but you can't do that, hence the error

The apparent asymmetry is due to the POSIX rules on how '.' is treated;
but we can't change the behavior of either of these commands, because
they are both following the POSIX rules.

If you want symmetry, omit the leading './', as in:

$ mkdir -p a/b/c
$ rmdir -p a/b/c

> 
> 1) thinking either rmdir shouldn't generate an error or mkdir should
> 
> mkdir -p a/../b      # no error

a needs to be created,
a/.. already exists, so it silently does nothing,
a/../b needs to be created

> rmdir -p a/../b      # error, but a & b removed

a/../b needs to be removed,
a/.. needs to be removed, but you can't do that,
at this point, POSIX is fuzzy whether to attempt to remove 'a', or to
give up since 'a/..' was already an error; but obviously coreutils
removes 'a'

> 
> 2) similar comment to above -- leading to:
> 
> for rmdir, if "-p" is used, then as similar to "mkdir -p":
>   (no error if existing, make parent directories as needed)
> 
> rmdir -p should be
>   "no error if dir not empty, but directories are followed
> and deleted as possible".

Sadly, while that might be a nicer definition for 'rmdir -p', it doesn't
match the POSIX requirements nor the historical behavior, so we can't
really change it now.

So I'm marking this as not a bug, as there is nothing to change.

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