--compare-dest apparently incompatible with --checksum or --size-only

Jesse Molina jesse at opendreams.net
Sat Dec 24 21:38:24 MST 2011

Thanks for your reply.

Just to be clear, when I said "delta-copy", I did not mean rsync's 
per-file delta to speed up remote transfers.  I meant that I am 
basically making an incremental backup of the directories in question.

I have a base-install dir (fresh set of files), a modified-install dir 
(some files modified, some deleted, some added), and the output, which 
should only include files changed or added in modified-install compared 
with base-install.

My use of -a is out of habit.  Thanks for the tip.  I will look into 
it's use in more detail.  However, what you are describing is basically 
what --copy-dest does, instead of --compare-dest.  My opinion is that 
the behavior which --compare-dest implies as desirable to the user would 
logically override and negate anything which would cause the same file 
to appear in the "delta-backup" output dir which was in the "original" 
dir below.

I suspect there is some tool out there which does exactly what I am 
trying to do, of which I am currently ignorant of, but I may have to end 
up writing a script which will hash the files to figure out what to 
copy, or use fdupes after a full copy to eliminate the copies produced.

Kevin Korb wrote:
> Hash: SHA1
> If you use -a then rsync will fix the time stamps if they are
> different.  Therefore rsync will have to copy them to fix the time
> stamps.  If you don't care about timestamps then don't tell rsync to
> sync them.
> Your source and target are both local paths.  That means that rsync is
> running with --whole-file forced.  It will not do a delta transfer
> anyways.
> On 12/24/11 22:21, Jesse Molina wrote:
>> I am working with rsync on Debian, package version 3.0.9-1.
>> I am trying to use rsync --compare-dest to make a delta-copy of a
>> directory.
>> In my case, the mtimes are all unreliable.  The data is the same,
>> but the times are all messed up and always will be.
>> I am trying to use --compare-dest with --checksum or --size-only
>> and it does not work.  All files are transferred and the delta copy
>> output is the same size as the local compared directory.
>> I would rather not use --size-only for obvious reasons (eh, 1, 0,
>> what's the difference?)
>> Example:
>> rsync -v -a --checksum --compare-dest=/original /modified
>> delta-backup
>> I could use fdupes to build a list instead, but it would be nice
>> if rsync would would.
>> Please correct me, document if this is true, or fix it.
>> Other ideas?
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# Jesse Molina
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