[TUHS] moving directories in svr2

Dan Cross crossd at gmail.com
Thu Dec 30 06:15:48 AEST 2021


On Wed, Dec 29, 2021 at 2:37 PM Dan Cross <crossd at gmail.com> wrote:
> The 4.3BSD man page has this gem: "Hard links may not refer to
> directories (unless the proper incantations are supplied) and may not
> span file systems." And indeed, a quick look at /usr/src/bin/ln.c on a
> VAX running 4.3 shows that it has an undocumented `-f` flag:
> presumably the "proper incantation" mentioned in the man page.

On a lark, I decided to check for this on 7th Edition as well. The man
page says, quite clearly: "It is forbidden to link to a directory or
to link across file systems." However, /usr/src/cmd/ln.c has the
undocumented `-f` flag, and if given, will elide checking for whether
the "name1" argument is a directory or not. Looking at the kernel, as
Doug mentioned, one must be the superuser to link a directory.

        - Dan C.


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