diff against existing files

[anarcat]

the diff command (#177) is great in finding out what changed between different archives. however, it would also be useful to diff against existing files. i know that you can use FUSE to mount an archive and use external tools to diff against that, but it seems to me there are optimizations that could be done with an internal diff command. for example, one could diff an individual file and avoid the overhead of doing the FUSE mount and looking down the directory tree...

There was a discussion on the mailing list recently that touched on this subject: https://mail.python.org/pipermail/borgbackup/2016q2/000202.html

[enkore]

borg lists --format option also supports common hashes, which could get the job done in many cases. Especially if one just wants to run shaXXXsum on some files.

[DrupaListo-com]

note: still no progress on that one, although in the upcomming 1.1 release you will be able to diff between already backed-up archives.

To sum it up.

1. diff against existing files - may be possible in one of 3 ways:
   1.1. use borg create -v --dry-run ... should work - I could not make it work - it ran but no diffs appeared on console
   1.2. borg mount and diff between live FS and the mount - painfully slow... but still doable - at least if u can mount the archives on localhost somehow (hard / impossible if your borg backups are remotely saved)
   1.3. just backup the live FS to create a new archive - and then diff this new one against the one before it using the latest git dev borg that is 1.1-dev-something. NOTE: borg diff does not exist in latest stable borg = 1.0.6, you need to install it via https://borgbackup.readthedocs.io/en/stable/installation.html#git-installation

and then from within the virtualenv where you have borg 1.1+ you can borg diff....
caveat 1: u will need to use sudo
caveat 2: u will need to use sudo + the full path to the borg executable in the venv...

[mortee]

Is this issue completely abandoned?

[ThomasWaldmann]

@mortee Issue is not closed.

But OTOH other stuff has higher priority and there are limited developer resources.

[ThomasWaldmann]

Somewhere I have read some hack combining borg and tar to implement that.

[ThomasWaldmann]

Also, an obvious solution is to create an archive from the "existing files" and then diff between archives. Considering that a new archive can be created rather quickly for most users, that sounds like an easy way and uses existing code.