Re: [Gnu-arch-users] arch with 'special files'

[John Arbash Meinel]

Josh England wrote:

> Hello,
>
> I'm evaluating arch (tla) to see if it is suitable for my very
> non-standard purpose.  I don't want to archive code, per se.  I want to
> archive a linux distribution, ie: '/' and everything underneath it.  I
> think the main problem is how to handle 'special' files such as
> block/character devices, fifos, etc.  It uses tar internally, right,
> which is certainly capable of managing devices files and such.
>
> It looks like arch is not inherently capable of handling these special
> kinds of files, but I thought I'd ask anyway:  Is there any way to use
> arch to handle this?  Does anyone know of a (clean) workaround to handle
> this?
>
> -JE

There is specific code in the inventory code to ignore anything that is
not a file, directory or symlink.

The specific code chunk is this:
     /* only symlinks, directories and plain files are
      * considerably source, all others need to be precious
      */
     if (   !S_ISREG (stat_buf.st_mode)
         && !S_ISLNK (stat_buf.st_mode)
         && !S_ISDIR (stat_buf.st_mode))
       {
         goto precious_file;
       }

I think the problem is how do you do a diff of a FIFO with another FIFO?
Is it just presence/absence?

You *really* don't want arch to consider /dev/hda as a file that it
would diff against some other /dev/hda.
Maybe for block items you would want to just record what their block
numbers. If you can come up with a reasonable definition, maybe it would
make sense.

But really that would be easier to do by having a script that you run
which takes inventory of whatever you want, and then puts that into a
text file. Then you use arch to manage the text file.

Arch also doesn't maintain owner/group. Again because that doesn't make
sense in standard revctl. Because if you put your source somewhere, I
download it, it shouldn't have you as the owner, it should have me.
Otherwise I might not even be able to read it.

Probably you don't want to use arch, because you really don't want to do
revision control. Unless you are trying to patch/merge the changes, you
should look into more of a backup system (like Amanda.)

John
=:->

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