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

[Bob Eager]

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?

-- 
Bob Eager