Re: setting up tracking on push

[Jay Soffian <jaysoffian@gmail.com>]

On Wed, Mar 11, 2009 at 8:58 PM, Jay Soffian <jaysoffian@gmail.com> wrote:

> http://article.gmane.org/gmane.comp.version-control.git/54822/

Let me summarize that thread as best I can.

- The branches under refs/remotes (those shown by "git branch -r") are
remote tracking branches. This is because they typically match (i.e.
track) the corresponding branch on a remote.

- The branches under refs/heads (those shown by "git branch") are your
local branches.

- Local branches can be associated with remote tracking branches in
the repo's config (.git/config). This association is done
automatically in current git when creating a new local branch based on
a remote tracking branch (e.g, git checkout -b topic origin/master or
git branch topic origin/master). (You can use --track and --no-track
to be explicit about whether or not you want the association to
happen.)

The association itself is simply an entry in the repo's .git/config. e.g.:

[branch "topic"]
        remote = origin
        merge = refs/heads/master

So, what does this entry in the .git/config do for you? A number of things:

1) git branch -v, git status, and git checkout will tell you how far
ahead/behind the local branch is from the associated remote tracking
branch.

2) git fetch, w/o arguments, will look in the config, find the remote
for the currently checked out branch, and update the configured
remote-tracking branches for said remote. This requires a bit more
explanation. In the above example, while topic is checked out, git
fetch will find that the associated remote is called "origin". It will
then update origin per its configuration, also in .git/config. e.g.:

[remote "origin"]
        url = git://git.kernel.org/pub/scm/git/git.git
        fetch = +refs/heads/*:refs/remotes/origin/*

So that tells git fetch where to fetch from, which remote branches to
fetch, and where to store those branches locally. In this case, each
branch under refs/heads/ on git://git.kernel.org/pub/scm/git/git.git
will be fetched and stored locally as refs/remotes/origin/. Locally
the branches are called "remote tracking branches".

3) git pull, w/o arguments, will run git fetch per above. It then
knows (in this example) to merge refs/remotes/origin/master into
refs/heads/topic. (The value on the "merge =" line is arguably
confusing because it is relative to where the branch is stored on the
remote, not where it is stored locally.)

HTH,

j.