On 2023-08-20 23:29, gah4 wrote:
> On Sunday, August 20, 2023 at 7:51:35 AM UTC-7, Johnny Billquist wrote:
>> On 2023-08-17 06:45, gah4 wrote:
>
> (snip)
>>> My favorite early VMS oops, is that you could rename a directory into itself.
>>>
>>> I think that was:
>>>
>>> REN X.DIR [-.X]
>>>
>>> The files go away, but quota isn't reduced, and I think the blocks are still in use.
>
>> Yeah. That would end up as a lost file (the directory), and then all
>> files beneath that would also be lost.
>> It can be recovered, but that requires running the disk checking tools.
>> Similar to fsck.
>
>> Same thing can happen/be done in RSX as well.
>
> I think it doesn't work anymore in VMS, but it did in early versions.

Yeah. I'm pretty sure they "fixed" that. However, there are more ways of
getting lost files. In VMS, as well as RSX, you can access files by file
id, and not only by path. That also means, you can even create files
that don't exist in any directory. That is a lost file already.
If you know the file id, you can still access the file. Also, you can
create and remove directory entries totally independent of the file,
unlike in Unix where everything is by pathname, and the inode number is
purely usable inside the kernel, and it's all reference counted.

> Pretty often in unix, I do:
>
> mkdir newdir
> mv * newdir
>
> to move all the files except newdir, and it works fine, though with a message.

I've done that a few times as well. :-)

> As well as I know, the blocks were recovered with disk tools, but they
> didn't give me the files back.

They should. In RSX, the tool is called VFY, and lost files are entered
into [1,3]. VMS should be doing the same. [1,3] is sortof the equivalent
of lost+found under Unix.

Johnny

Johnny Billquist <bqt@softjar.se> writes:
> ... In VMS, as well as RSX, you can access files by file
> id, and not only by path.

How is this done? I'd like to try it out. Thanks!

Andy Valencia
Home page: https://www.vsta.org/andy/
To contact me: https://www.vsta.org/contact/andy.html

On 2023-08-25 01:46, Andy Valencia wrote:
> Johnny Billquist <bqt@softjar.se> writes:
>> ... In VMS, as well as RSX, you can access files by file
>> id, and not only by path.
>
> How is this done? I'd like to try it out. Thanks!

In RSX you normally access files using FCS or RMS. The library calls to
open a file have a variant where you give just the file ID to the call.
For higher level languages, it depends on what functions have been made
available in that language. (I could write up an example on how to do it
from PDP-11 C and RMS, but with most other languages I would need to
throw in a bit of Macro-11 as well.)

On the command line, it equally depends on if the tools have a way or not.

PIP do. If you want to look at a file purely based on the file ID:

PIP TI:=<device>:/FI:<filenum>:<seqnum>

If you want to see the id of a file:
PIP <filename>/FU

Example:

..pip m.txt/fu

Directory DU0:[BQT]
25-AUG-23 11:34

M.TXT;1 (17460,1436) 1./1. 07-JAN-13 20:14
[7,14] [RWED,RWED,RWED,R]

Total of 1./1. blocks in 1. file

..pip ti:=m.txt
rmd, build rth devices,
..pip ti:=/fi:17460:1436
rmd, build rth devices,

Of course you can do anything with the file id in PIP. Delete the file,
copy the file, create another directory entry for the file, and so on.
Note that if you delete a file this way, the directory entry will still
hang around, but will no longer point to an existing file.
And if you remove the directory entry for a file without deleting it,
you will have a "lost" file. You can still access if through the file
id, though. And VFY can find such files and enter them into [1,3].

Exactly how you go about in VMS, is a little more unknown to me. You can
obviously use RMS to access the file, but high level languages, as well
as command line I know less.

Johnny Billquist <bqt@softjar.se> writes:
> >> ... In VMS, as well as RSX, you can access files by file
> >> id, and not only by path.
> > How is this done? I'd like to try it out. Thanks!
> In RSX you normally access files using FCS or RMS. The library calls to
> open a file have a variant where you give just the file ID to the call.
> ...

Thank you!

Andy Valencia
Home page: https://www.vsta.org/andy/
To contact me: https://www.vsta.org/contact/andy.html

On 2023-08-26 20:12, Andy Valencia wrote:
> Johnny Billquist <bqt@softjar.se> writes:
>>>> ... In VMS, as well as RSX, you can access files by file
>>>> id, and not only by path.
>>> How is this done? I'd like to try it out. Thanks!
>> In RSX you normally access files using FCS or RMS. The library calls to
>> open a file have a variant where you give just the file ID to the call.
>> ...
>
> Thank you!

By the way. The FCS and RMS libraries are actually the ones doing the
lookups on filenames giving a file id as well. The actual I/O request to
open a file is always using the file id. So the whole filename to id
lookup/translation happens in userspace in your program. Including also
the multiple directory traversion.

Johnny