From: Will Senn <will.senn@gmail.com>
To: Clem Cole <clemc@ccc.com>
Cc: TUHS main list <tuhs@minnie.tuhs.org>
Subject: Re: [TUHS] moving directories in svr2
Date: Wed, 29 Dec 2021 09:44:32 -0600 [thread overview]
Message-ID: <d5b6f210-84e0-d9c7-3360-11e1dcbb6fcc@gmail.com> (raw)
In-Reply-To: <CAC20D2MozATvG1AK_QJe5ghz9NPL=vtW4dox7z0vShB-7nL+eQ@mail.gmail.com>
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On 12/29/21 9:17 AM, Clem Cole wrote:
> Not until the BSD rename system call,.
>
> Try it on V6 or V7 and you will get 'directory exists' as an error.
>
Sure enough. I never really noticed. I guess cuz I was careful about
creating directories in the first place.
> Think about the UNIX FS and the link system call. How is mv
> implemented? You link the file to the new directory and the unlink
> it from the old one. But a directory file can not be in two
> directories at the same time as the .. link would fail. When Joy
> created the rename system call it became possible. Until System V
> picked it up (IIRC was SVR3), only system that supported the BSD world.
>
Nice summary. I will add it to my systems programming investigations list.
> What I have forgotten is if the BSD mv command for 4.1 supported it.
> If it did then it was not atomic -- it would have had to create the
> new directory, move the contents independently and then remove the old
> one.
>
> FWIW: when we did the first SMP UNIX at Masscomp we had supported the
> BSD FS and the 4.1c/4.2 system calls. Joy's implementation of rename
> was a real mess. Making it atomic, supporting an SMP and deal with
> all the recovery paths on an error took some work. It's funny, the
> rename system call is a simple idea, but on a failure when
> partially thru it, makes unwinding the partial completion an
> interesting problem.
It's impressive what early work was done and how few today really
understand the challenges that were met and overcome to give us our
cushy oses.
>
> Clem
>
> On Wed, Dec 29, 2021 at 9:34 AM Will Senn <will.senn@gmail.com> wrote:
>
> I'm a little flummoxed in trying to move some directories around
> in svr2. Shouldn't the following work?
>
> mkdir a
> mkdir b
> mv a b
>
> I get the following error:
> mv: b exists
>
> I tried many of the possible variants including:
>
> mv a b/
> mv: b/ exists
> mv a b/a
> mv: directory rename only
> cd b
> mv ../a .
> mv: . exists
> mv ../a ./
> mv: ./ exists
> mv ../a ./a
> mv: directory rename only
>
>
> If moving directories into existing directories wasn't allowed in
> those days, 1) how were directories managed? and 2) when did
> moving directories into directories become a thing?
>
>
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next prev parent reply other threads:[~2021-12-29 15:44 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
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 [this message]
2021-12-29 16:10 ` Clem Cole
2021-12-29 16:33 ` Warner Losh
2021-12-29 16:01 ` Bakul Shah
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 17:12 Douglas McIlroy
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
2021-12-29 21:20 ` Clem Cole
2021-12-30 3:15 ` Bakul Shah
2021-12-29 19:33 Noel Chiappa
2021-12-30 3:40 ` Jay Logue via TUHS
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
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