How can I see which Git branches are tracking which remote / upstream branch?

Very much a porcelain command, not good if you want this for scripting:

git branch -vv   # doubly verbose!

Note that with git 1.8.3, that upstream branch is displayed in blue (see "What is this branch tracking (if anything) in git?")

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If you want clean output, see Carl Suster's answer - it uses a porcelain command that I don't believe existed at the time I originally wrote this answer, so it's a bit more concise and works with branches configured for rebase, not just merge.

An alternative to kubi's answer is to have a look at the .git/config file which shows the local repository configuration:

cat .git/config

If you look at the man page for git-rev-parse, you'll see the following syntax is described:

<branchname>@{upstream}, e.g. master@{upstream}, @{u}

The suffix @{upstream} to a branchname (short form <branchname>@{u}) refers to the branch that the branch specified by branchname is set to build on top of. A missing branchname defaults to the current one.

Hence to find the upstream of the branch master, you would do:

git rev-parse --abbrev-ref master@{upstream}
# => origin/master

To print out the information for each branch, you could do something like:

while read branch; do
  upstream=$(git rev-parse --abbrev-ref $branch@{upstream} 2>/dev/null)
  if [[ $? == 0 ]]; then
    echo $branch tracks $upstream
  else
    echo $branch has no upstream configured
  fi
done < <(git for-each-ref --format='%(refname:short)' refs/heads/*)

# Output:
# master tracks origin/master
# ...

This is cleaner than parsing refs and config manually.

git remote show origin

Replace 'origin' with whatever the name of your remote is.