Hardlink sub-directories and files

[Grant Edwards]

On 2011-08-03, Kushal Kumaran <kushal.kumaran+python at gmail.com> wrote:
> On Wed, Aug 3, 2011 at 7:29 AM, Dan Stromberg <drsalists at gmail.com> wrote:
>>
>> On Tue, Aug 2, 2011 at 3:13 AM, Thomas Jollans <t at jollybox.de> wrote:
>>>
>>> On 02/08/11 11:32, loial wrote:
>>> > I am trying to hardlink all files in a directory structure using
>>> > os.link.
>>> >
>>> > However I do not think it is possible to hard link directories ?
>>
>> That is pretty true.?? I've heard of hardlinked directories on Solaris, but
>> that's kind of an exception to the general rule.
>
> In APUE, Richard Stevens says only root could do this,

Yep, in early versions of Solaris root could hard-link directories.
I did it once, and it's not something one did a second time.  fsck
couldn't deal with it and pretty much fell over.  IIRC, the only way
to recover was to clear several inodes manually and then let fsck
salvage things.

> if it is supported by the system at all.  In a footnote, he
> additionally mentions he screwed up his filesystem by creating a loop
> of hardlinked directories while writing that section of the book.

That sounds about right.

> I suppose it is a good thing systems don't allow that now.

It wouldn't be a problem, except there are some important places in
Unix where it is assume that filesystems are trees.  Hard linking
directories causes that assumption to be false.

-- 
Grant Edwards               grant.b.edwards        Yow! Somewhere in DOWNTOWN
                                  at               BURBANK a prostitute is
                              gmail.com            OVERCOOKING a LAMB CHOP!!