The Unix Heritage Society mailing list
 help / color / mirror / Atom feed
From: Dan Cross <crossd@gmail.com>
To: Richard Salz <rich.salz@gmail.com>
Cc: TUHS main list <tuhs@minnie.tuhs.org>,
	Douglas McIlroy <douglas.mcilroy@dartmouth.edu>
Subject: Re: [TUHS] moving directories in svr2
Date: Wed, 29 Dec 2021 15:58:10 -0500	[thread overview]
Message-ID: <CAEoi9W4MWampirvU609UpFdb7E=77UwhyHi16CH7gEcc_z9XxQ@mail.gmail.com> (raw)
In-Reply-To: <CAFH29tqKbwg2-s7LYjM-eY9w+Odt_94f3a82HnVdyHfaNuW3yA@mail.gmail.com>

Partitioning the tree sure seems like it would lead to a bad day, doesn't it?

I expect the undocumented arcana related to linking directories was
always an escape hatch for a skilled administrator to rescue a sick
system. One can imagine any number of ways in which directory files
could be corrupted; sufficient inspection of disk contents might give
someone with the requisite low-level knowledge sufficient information
that they could, say, reattach a pruned subtree with clever uses of
`ln -f` and `unlink`. Did `icheck` and friends have something
analogous to the `lost+found` directory created by `fsck`? I could
imagine (somewhat painfully) executing those commands while in
single-user mode on the console.

        - Dan C.

On Wed, Dec 29, 2021 at 3:42 PM Richard Salz <rich.salz@gmail.com> wrote:
>
> https://dsf.berkeley.edu/cs262/unix.pdf section 3.2 ends with:
>
> Each directory always has at least two entries. The
> name "." in each directory refers to the directory itself. Thus a
> program may read the current directory under the name “.”
> without knowing its complete path name. The name “..” by
> convention refers to the parent of the directory in which it
> appears, that is, to the directory in which it was created.
> The directory structure is constrained to have the form
> of a rooted tree. Except for the special entries “.” and “..”,
> each directory must appear as an entry in exactly one other,
> which is its parent. The reason for this is to simplify the
> writing of programs which visit subtrees of the directory
> structure, and more important, to avoid the separation of
> portions of the hierarchy. If arbitrary links to directories
> were permitted, it would be quite difficult to detect when
> the last connection from the root to a directory was severed

  reply	other threads:[~2021-12-29 20:59 UTC|newest]

Thread overview: 71+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-29 19:13 Douglas McIlroy
2021-12-29 19:37 ` Dan Cross
2021-12-29 20:15   ` Dan Cross
2021-12-29 20:42     ` Richard Salz
2021-12-29 20:58       ` Dan Cross [this message]
2021-12-29 21:20         ` Clem Cole
2021-12-30  3:15       ` Bakul Shah
  -- strict thread matches above, loose matches on Subject: below --
2021-12-30  3:45 Noel Chiappa
2021-12-30  4:02 ` Bakul Shah
2021-12-30 16:40 ` Theodore Ts'o
2021-12-30 22:31   ` Dan Cross
2021-12-31  0:43     ` Bakul Shah
2021-12-31  1:00       ` Rob Pike
2021-12-31  1:45         ` Bakul Shah
2021-12-31  2:23           ` Adam Thornton
2021-12-31 18:56       ` Chet Ramey
2021-12-31  3:08     ` Theodore Ts'o
2021-12-31  3:23       ` Rob Pike
2021-12-31  5:16         ` Theodore Ts'o
2021-12-31  5:21           ` Dan Cross
2021-12-31  5:55           ` Rob Pike
2021-12-31 13:32             ` Michael Kjörling
2021-12-31 15:53               ` Adam Thornton
2021-12-31 16:13                 ` Arthur Krewat
2021-12-31 18:17                 ` Dan Cross
2021-12-31 18:23                   ` Larry McVoy
2021-12-31 18:37                     ` Dan Cross
2021-12-31 18:29                   ` Arthur Krewat
2022-01-01  0:09                   ` Theodore Ts'o
2022-01-03 13:35                     ` Dan Cross
2022-01-03 20:23                       ` Theodore Ts'o
2022-01-03 20:45                         ` Warner Losh
2022-01-03 21:15                         ` Dan Cross
2022-01-03 22:26                           ` Theodore Ts'o
2022-01-03 23:10                             ` Dan Cross
2022-01-04 15:45                             ` Chet Ramey
2022-01-09 19:28                             ` Larry McVoy
2022-01-03 23:21                           ` Doug McIntyre
2022-01-03 23:37                             ` Adam Thornton
2022-01-04 14:49                               ` Stuart Remphrey
2022-01-03 23:44                             ` Larry McVoy
2022-01-03 23:56                               ` Warner Losh
2022-01-04  2:28                               ` Theodore Ts'o
2022-01-04  2:42                                 ` Larry McVoy
2022-01-03 22:57                         ` Phil Budne
2021-12-31  5:12       ` Bakul Shah
2021-12-29 19:33 Noel Chiappa
2021-12-30  3:40 ` Jay Logue via TUHS
2021-12-29 17:12 Douglas McIlroy
2021-12-29 16:59 Bakul Shah
2021-12-29 17:04 ` Clem Cole
2021-12-29 17:14 ` arnold
2021-12-29 17:38   ` Clem Cole
2021-12-29 17:49     ` Brantley Coile
2021-12-29 18:27       ` ron minnich
2021-12-29 20:59         ` Rob Pike
2021-12-29 14:33 Will Senn
2021-12-29 15:02 ` arnold
2021-12-29 15:38   ` Will Senn
2021-12-29 15:44     ` Richard Salz
2021-12-29 16:17       ` Clem Cole
2021-12-29 16:58         ` Richard Salz
2021-12-30  5:14         ` Dan Stromberg
2021-12-30 16:22           ` Clem Cole
2021-12-30 18:02           ` John Cowan
2021-12-30 23:04             ` Richard Salz
2021-12-29 15:17 ` Clem Cole
2021-12-29 15:44   ` Will Senn
2021-12-29 16:10     ` Clem Cole
2021-12-29 16:33       ` Warner Losh
2021-12-29 16:01   ` Bakul Shah

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAEoi9W4MWampirvU609UpFdb7E=77UwhyHi16CH7gEcc_z9XxQ@mail.gmail.com' \
    --to=crossd@gmail.com \
    --cc=douglas.mcilroy@dartmouth.edu \
    --cc=rich.salz@gmail.com \
    --cc=tuhs@minnie.tuhs.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).