Shatag

I just got a tip about using shatag, a tool which annotates files with their checksum, using posix file attributes. This is a terrific tool!

On Debian testing, install it with:

apt-get install shatag
apt-get install attr

I use btrfs which supports xattr by default, but you may need to turn it on for other filesystems.

And then, as a regular user:

shatag -tv file
getfattr -d file

and you should be able to see the checksum of the file.

It is just great with people emailing me with suggestions and ideas for rdfind. Thanks Andrea Trentini for sending me the tip! The idea is to use shatag to retrieve the checksum, which makes less work to find duplicates later.
A typical workflow could be:

shatag -rt /path/to/check
rdfind /path/to/check

but off course rdfind would need some changes in order to read the checksum from disk. One option would be to let rdfind store the checksum directly, obliviating the need for shatag. Something along

rdfind -usexattr true /path/to/check

or so.