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Number   :  4116
Date     :  2003-03-24
Author   :  Garry Deane
Subject  :  Re: using xxcopy together with zip/arj compression
Size(KB) :  2


--- In xxcopy@yahoogroups.com, anders thoresson  wrote:

> XXCOPY \src\ \ref\ /CLONE /TR0
> 
> - creates a reference directory tree which contains
> every directory and every file in \src\ but with the
> files truncated to 0 bytes.

Correct

> XXCOPY \src\ /AZ /S
> 
> - removes the archive bit from every file in \src\

Correct

> XXCOPY \src\ \ref\ /AA /S /H /U /BX
> 
> - for every file, hidden or not, in \src\ that doesn't
> exist in \ref\ or where the file in \src\ has been
> modified, the archive bit is set.

The intention is correct but see below.

> the /U switch also updates the same files in \ref\.

No, /U excludes files in \src\ which are not in \ref\ (only acts on 
files which are in both \src\ and \ref\) from having the archive bit 
set. In fact, this switch should NOT be used (or use /U0) because you 
want any new files in \src\ to have their archive bit set.

> But why is the /TR0 switch not included here?
> Are even new files that are added to \ref\ truncated
> to 0 bytes?

The /AA switch sets the archive bit of files in \src but does NOT do 
any copying. \dest\ is not updated or changed in any way. After your 
incremental backup has completed successfully, you would issue the 
Xxcopy \src\ \ref\ /clone /tr0 again to update the reference 
directory. Although xtb#11 shows this as the first command, this is 
to assist the explanation and 'prime the pump'. In practice, it would 
also be the last command in a batch procedure but you need to ensure 
that the incremental backup was successful before doing this 
otherwise you'll lose track of the changes.

> XXCOPY \src\ \dst\ /A /S /H /KS
> 
> - every file in \src\ which has the archive bit set is
> copied to \dst\. /KS makes sure that if the file is read-only
> in \src\ it's read-only in \dst\ as well.

Correct

> Is this a correct description of the for steps included
> in "Differential Backup using a skeleton directory" in TB#11?
> 
> The text in the bulletin states that "for illustration
> purpose, common switches are deliberately left out". Which
> switches should be added to have a working backup-set?

You usually add switches to suppress prompts, create a log of 
activity, sometimes to specify an exclusion file list, sometimes to 
allow a cyclic redundancy copy etc. In a batch file, you would 
probably have /CB to terminate if the previous Xxcopy command 
produced an error. See Xxcopy /bu /? for the switches used in the 
backup operation for a typical list.

Note that you can get a brief explanation of the meaning of the 
switches using /? e.g. Xxcopy /AA /S /H /BX /?.

Garry



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