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Number   :  4705
Date     :  2003-06-02
Author   :  Kan Yabumoto
Subject  :  Re: Exclusion Question
Size(KB) :  3



Garry wrote:



> To use the example given by "edlight0" where he wants to
> restore from a backup but preserve some selected files,
> instead of using /CLONE, he can use the following 2 step
> process:

> :: Step 1 - copy any changed files from the backup
>
> xxcopy D:\backup\ C:\ /backup/xpagefile.sys/xhiberfil.sys
>
> :: Step 2 - delete any extra files in C:\ if they don't
> :: exist in the backup but keep pagefile.sys and hiberfil.sys
>
> xxcopy C:\ D:\backup\ /bu/rsy/pd0/xpagefile.sys/xhiberfil.sys
>

We know Garry is often better than the author of XXCOPY in
exploiting the features from the users perspective.

Here, Garry's suggestion had an inadvertent typo error
(it could have come from my earlier typo error --- entirely
possible.)

The second xxcopy command should use /BB/RSY rather than
/BU/RSY. That is, we want to delete unique files in the
C:\ directory rather than common files in both C:\ and
D:\backup\ directories.

Other than the typographic correction, I fully agree with
Garry. The /Z and /ZY switch is simple and elegant on
what it does. It is care-free with little to worry about.

Since changing the behavior of XXCOPY with respect to
the /Z action is very unpopular and we have little
justification to do so. After all, the /Z switch is
not broken.

Let me summarize what options you have with respect to
backup, restore, the /Z action, and exclusion.

1. We have two variations in general selective copy
operations

xxcopy \dir1\ \dir2\ /clone // with /ZY
xxcopy \dir1\ \dir2\ /backup // without /Z

2. Adding /X or /EX will affect file selection in the
source directory (\dir1\)

3. The /Z (and /ZY, also in /CLONE) action is determined
solely by absence of the counterpart in the source
directory (no other switches such as exclusion or
inclusion operations affects the /Z action).

If there are files in the destination directory that
you do not wish to be deleted by the /Z action, you
probably should not use the /Z (or /CLONE) switch.

Instead, do the copy (you may call it "restore")
operation without deleting anything (with /BACKUP
rather than /CLONE), and in the following step,
swap the arguments in the XXCOPY command and run
a /RSY operation with exclusion features you like.

Let me generalize what Garry wanted to say.
Here's a very common backup (and restore) operation.

xxcopy \dir1\ \dir2\ /clone

It can be re-written as the following two-step operation

xxcopy \dir1\ \dir2\ /backup
xxcopy \dir2\ \dir1\ /rsy/bb/s/r/h/q

Note: here, the order of the directories entered in
the second command line is opposite of the first one.
The important thing here is that /Z on the destination
directory is equivalent to /RSY/BB on the source directory.

The advantage of the two-step method is that in each
operation we focus the operation into one thing
(file-copy in the first step, and file-delete in the
second step). The rich set of the XXCOPY file-selection
mechanism can be fully exploited when you put the
second directory (\dir2\) in the center stage. It includes
file selections

by name patterns /X, /EX,
by size /SZ:
by filedate /DA: /DB: /DO:,...
by attributes /A, /M, /H, /Ho, /AT, /AX,...

Probably it would be a mistake if we start adding
variations to all these switches which will affects
only on the files that would otherwise be selected
by the /Z action.

Kan Yabumoto



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