How to force checksum in dry-run

[Kevin Korb]

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On 12/21/2014 03:40 PM, eightfold ? wrote:
> I chose rsync over diff -r because diff -r is a binary comparison
> and it takes longer than creating a checksum. Isn't that correct?

Diff should be faster as it stops comparing (in binary mode) when it
finds a difference.  There is no reason to continue reading the files
once they are known to be different.  It may even have an initial size
difference check that would mean it wouldn't have to read the files at
all.

> I did not understand this:
>> Rsync isn't even smart enough to not bother checksumming things
>> that
> don't even have a comparison file.

If a file is only on the source or the target then there is no
opposite file to compare it to.  Rsync will still read the file and
calculate the checksum.  If the file sizes are different rsync will
still read and checksum both of them even though they should not match
(if they do something much fishier than whatever has you wanting to
checksum your files is going on).

> --checksum seems to work as you say even in --dry-run mode. At
> least it takes a lot of time, which should be a good sign.
> 
>> Date: Sat, 20 Dec 2014 21:57:02 -0500 From: kmk at sanitarium.net 
>> To: rsync at lists.samba.org Subject: Re: How to force checksum in
>> dry-run
>> 
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>> 
>> It will work but why not just use diff -r ? Or a dedicated file 
>> validation utility like cfv?
>> 
>> Rsync isn't even smart enough to not bother checksumming things
>> that don't even have a comparison file.
>> 
>> On 12/20/2014 09:42 PM, eightfold ? wrote:
>>> I want to use rsync to diff two folders (with checksum) by
>>> using dry-run and itemize changes like this: rsync -rni
>>> --checksum /dir1/ /dir2/> ~/Desktop/diff.log
>>> 
>>> However, I read that in --dry-run rsync wont do checksums. Is
>>> this true? If it is, is there a way to force checksums i
>>> dry-run mode?
> 
> 

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	Kevin Korb			Phone:    (407) 252-6853
	Systems Administrator		Internet:
	FutureQuest, Inc.		Kevin at FutureQuest.net  (work)
	Orlando, Florida		kmk at sanitarium.net (personal)
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