Is there a howto/tutorial on backups/rsync that covers the use of hard and soft links?

Joe josephj at
Tue Jan 22 00:31:38 MST 2013

There have been a lot of posts on the list lately about issues with hard
links.  It has been very interesting, but I don't understand it very
thoroughly.  I haven't used hard links for anything yet.  I've used
symlinks - not for backups, of course - and have seen them get broken or
deleted in backups.

Is there a tutorial anywhere that will explain how this works (assuming
that the reader understands the basic concepts of backups and knows how
to program, but doesn't really understand how to use links to create
things like incremental or differential backups)?  It seems like there
are a lot of fine points to consider, some of which can really bite you
if you don't take them into account.

I'm working on my own personal backup system using bash and rsync.  When
it's done it will be pretty good, but it would be *much* better if I
rewrote it to have more backup versions using hard links to save space.

I am writing my own because (aside from learning a lot) I have only seen
two types of backup utilities - those that are very simplistic and won't
let me do what I want and those which are enterprise level and I can't
figure out how to get them to do anything without extensive study.  (I
did experiment with areca (I think it uses rsync libraries under the
hood) which would probably do everything I want, but I got stuck too
many times and couldn't get enough support on their forum to keep going.)


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