How do I check if git branch has a tracking branch?

Question

I'm writing a small git helper for bash and I need to know whether the branch of some name has a tracking branch or not.

More specifically the problem is that if you run git pull on a branch which doesn't have a tracking branch it will fail with the following:

There is no tracking information for the current branch.
Please specify which branch you want to merge with.
See git-pull(1) for details

git pull <remote> <branch>

If you wish to set tracking information for this branch you can do so with:

git branch --set-upstream-to=origin/<branch> foo

git pull --quiet also doesn't suppress this message.

I've managed to find this useful shortcut:

git rev-parse --symbolic --abbrev-ref foo@{u}

It does exactly what I need, and outputs the following, if tracking branch is present:

origin/foo

But if a branch doesn't have tracking branch, here's the output:

fatal: No upstream configured for branch 'foo'

This is fairly ok, except that it exists with non-zero status, and outputs this to stderr.

So what I basically want to do is:

tracking_branch=$(git do-some-magick foo)
if [[ -n $tracking_branch ]]; then
    git pull
fi

Instead of this:

tracking_branch=$(git rev-parse --symbolic --abbrev-ref foo@{u} 2> /dev/null)
if [[ -n $tracking_branch ]]; then
    git pull
fi

It actually works fine, but doesn't seem right to me. Are there any other ways to do this?

Answer 1

You can try this to find the tracking branch:

git config --get branch.foo.merge

Examples:

$ git config --get branch.master.merge
refs/heads/master

$ git config --get branch.foo.merge # <- nothing printed for non-tracked branch "foo"

The information about tracking branches are stored in repository specific .git/config , according to the manual for git pull :

Default values for <repository> and <branch> are read from the "remote" and "merge" configuration for the current branch as set by git-branch[1] --track.