Is there any way to restore/create hardlinks lost in incremental backups?

[Guillaume Outters]

On 2020-12-11 12:53, Chris Green wrote :

> […] wrote a trivial[ish] script that copied
> all the backups to a new destination sequentially (using --link-dest)
> and then removed the original tree, having checked the new backups
> were OK of course.

With the same cause as yours, I once worked out exactly the same 
solution.

But then, having to automate it, I worked a bit more on it, and ended 
up having a shell script that:
- recursively listed files as "file size - inode - path"
- with sort and awk, output the list of "every size that has different 
inodes"
- for each output size, cksumed one file for each inode
- if two different inodes (with the same file size) had their cksum 
match, then it replaced every file for the last inode, with a link to 
the first inode

If you have to run it frequently, you may want to implement something 
similar.
Although it ignores mtime info (and thus strips it when lning),
it has the great benefit of finding every duplicate, be it renamed and 
move to another dir
(as in 
./her.2020-12-01/Library/Mail/…/Sent.mbox/…/Attachments/…/PhotoDeFamille.JPG 
versus ./his.2020-11-26/perso/photos/100_9999.JPG).

(and by the way I reimplemented it in C, "just for fun" and for speed 
too: https://github.com/outtersg/dude/ . Hmm, in C but in French)

-- 
Guillaume