Hi,
I'm wondering how dangerous the interaction of git with the unison

file synchronizer[1] can be.
Another way of asking the question can be: what's the best way to

keep two machines with many git repositories in sync?
Unison is a userland application that does bi-directional

synchronization of two directories. Typically, to keep a laptop and a

desktop synchronized (modify a file on the desktop and another on the

laptop, unison will copy the files). I find it very usefull to keep

large directories containing unrelated projects (typically,

~/teaching/, ~/research, ..., my colleagues even synchronize $HOME on

their laptops) in sync between two machines.
Actually, git achives something similar (and lot more, of course):

modify a file here, commit, modify another there, commit, and then

push & pull can do the sync. I find git excellent to manage somehow

self-contained projects (~/teaching/2007-2008/whatever-course/), but

inappropriate for $HOME or such big containers (need to run more

commands, disk-space overhead, ...).
So, at the moment, I have both unison and git. My fear is that unison

touches the content of the .git/ directories. So, for example, if I

commit on one side, and commit something else on the other side, I'll

get unison conflicts at least on .git/refs/heads/master and

.git/index, and resolving the conflict in favor of either side leads

to dangling objects whith important content.
What I'm doing right now is that I try to make sure I don't run unison

when trees have diverged, which is not really satisfactory since 1) I

can be wrong, and a miss-synchronization could lead to data-loss, and

2) that means not really taking advantage of unison.
What about you? What do you use to synchronize your laptop and

desktop, or home and office? Anybody using unison and git on the same

filesystem?
Thanks for your hints,
--

Matthieu
[1] : http://www.cis.upenn.edu/~bcpierce/unison/

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I just have a subdirectory of my home directory "local" that I tell

unison not to synchronize:
	ignore = Path local
and keep all my git repos there, relying on git itself when I need to

distribute stuff--generally all my repos are associated with public

repos on a single (regularly backed-up) server, and I try not to let any

work accumulate in any particular repository for long without being

pushed to a branch in its public repo.
--b.

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[...]

Note that I do use I do use both unison and git, but I don't use
Well, at least with my configuration, when a file have been change on

both side, unison offer the possibility to transfer one way or the

other or to do nothing. I believe that if this happen, the correct

procure is to use git tool to merge (as git is better for merging
Well, as I've already said, I use unison in an interactive way, so if

a file have been changed in both side, unison say it, ask me what to

do. So I can choose to do nothing, and to stop unison right away to

use a better tool for this task.
--

Rémi Vanicat

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