Verifying backups

Ronald F. Guilmette rfg at
Wed Sep 30 22:42:52 UTC 2015

Kevin Korb <kmk at>,

I thank you greatly for your attempts to educate me, however as we get
deeper into discussing more and more different rsync options, I feel
that I am actually just getting more confused and frustrated.  I've been
sitting here, trying all sorts of different combinations and permutations
of the various options we've discussed, and that you've told me about,
but so far none of the combinations is producing the (seemingly simple)
effect that I wanted.

So, at the risk of trying your patience, may I please request that we
begin again.  Let's start from scratch, and perhaps you can guide me to
the simplest possible solution to the problem I first came here with...
hopefully a solution which is so simple that even *I* can't screw it up.

So, let's consider the following simple hypothetical example...

We have two directories within the current directory.  They are named
./one/ and ./two/

Within each of these two directories, there is a set of ordinary files.
The set of filenames present within each of the two directories is
identical.  Let's just say that each one contains the following
three ordinary files:


How may I use rsync to obtain a list of _just_ those files within these
two directories that the cmp command would describe as being different
between the two directories?  What is the exact command line I should use?
(And within the output from the given command, what must I look for,
exactly, that designates files that are different, as opposed to those
whose content is the same?)


P.S.  I really do hope that I can get this to work with rsync.  I do
prefer not reinventing the wheel, but it is starting to seem simpler
to me if I were to just write a Perl script that would walk two directory
hierarchies, in parallel, and just repeatedly invoke the cmp command on
all of the regular files found therein.

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