[Info-vax] Request description of UFS for VMS person

[Richard B. Gilbert]

Bob Eager wrote:
> On Thu, 30 Apr 2009 20:15:33 UTC, AEF <spamsink2001 at yahoo.com> wrote:
> 
>> On Apr 30, 3:05 pm, "Bob Eager" <rd... at spamcop.net> wrote:
>>> On Thu, 30 Apr 2009 18:21:29 UTC, AEF <spamsink2... at yahoo.com> wrote:
>>>> The whole point of "everything in Unix is a file" to me means that you
>>>> can treat all these things as files the same way. In ODS-2 everything
>>>> is a file or is in a file. You can dump any file, even the pagefile! I
>>>> don't have to write no stinkin' utilities. I can use file commands on
>>>> VMS files. I can't use file commands on the super block or an inode.
>>>> So in my book they are not "files". If files are as you define them,
>>>> then the claim "everything in Unix is just a file" becomes
>>>> meaningless.
>>> You're getting hung up on this phrase, which was just a shorthand for
>>> "everything in UNIX can be accessed by file I/O operations".
>> I've never heard that. And if so, so what?
> 
> Just saying, you're hung up on this phrase. But then you're intent on 
> X-knocking, whenever X is not VMS. 
> 
>>> So, to use 'od' on the superblock in my FreeBSD system:
>>>
>>> dd if=/dev/ad4s1a skip=65536 count=1
>> If it were a file, I wouldn't need to do this.
> 
> Agreed. But so what? I have demonstrated that you don't need to write a 
> utility, and now you're moving the goalposts.
> 
>>> and pipe it into 'od' (I didn't show that as this newsreader is refusing
>>> to do the pipe symbol)
>>>
>>> Of, course, that's just one superblock; there are usually many copies.
>>>
>>>> I just want to know in what sense super blocks and inodes are files.
>>> Not sure where you got the original quote from anyway. It's a loose way
>>> of saying that all I/O is via files. OK< you may think it's a
>>> shortcoming that bits of disk data structures aren't available directly
>>> as their own files (they are available as parts of files, though). But
>> Then they're not files. (What disk strucutres are available as "part
>> of files", and what's the point? Are super blocks and inodes parts of
>> files?) I can use file commands on files: cp, rm, mv, etc. I can't use
>> these on super blocks or inodes. Therefore, super blocks or inodes are
>> not files. I never heard "file I/O operations". I heard files.
> 
> Then you had insufficjent comprehension of what was said.
> 
>>> Different doesn't mean bad. Live with it.
>> I never said either OS was better or worse. I was just saying that not
>> everything is a file in Unix. On an ODS-2 disk, everything is a file
>> and all the file commands pretty much work the same way on all the
>> files. In particular, you can DUMP any file. I never have to invoke
>> strange dd commands or write utilities. Everything on the disk really
>> *is* a file.
> 
> How would you dump the file header for the file with file ID (2341,0,0),
> for example? Without using a special utility? And not dumping all the 
> others?
> 

$ DUMP /HEADER <mumble>

<mumble> would normally be the file name.  There are other ways to 
access the file than by name but I would have to look them up.  It has 
been many years since I have needed to do so.