Buvt (Back Up and Verification Tool)
Disclaimer
The tools is offered as is, bugs may appear, test the functionalities you want to use on a test environment first.
There are several ways to use the tool to mess up the "Target-tree" (the back up) and the "metafile" (file with hash codes).
The "Source-tree" (original files) are never touched* except for the "metafile" (which by default is located at root level in the Source-tree).
(*) "Never touched" assuming you don't let the target and source trees intersect.
Why is it needed? (why not use rsync). Answer: It is important to minimize the amount of copying when backing up (and calculating hash codes)
Unnecessary copying propagates soft errors (and takes unnecessary time)
So when a file is renamed one preferably wants the backed up file to be renamed too (rather deleting and rewriting it).
Same for the verification (hash) code, if a soft error has occurred in your original file, you '''don't''' want the code to be recalculated and overwritten. (You want the hash-code to be recalculated when you "check" your files some time later)
Filter
Files (default called ".buvt_filter") can be placed in the Source-tree to make it possible to skip certain files and folders.
They work pretty much as ".rsync-filter" do for rsync (as a matter of fact I considered using the same file (and syntax) as rsync, but I had to give up on that because I can't figure out how rsync works)