What_git_push_pushes.md

What Git Push pushes

How it works

git push <remote> <branch> pushes exactly the branch <branch> to the same named branch on remote <remote>. You can always use this form to achieve full control.

$ git push origin master

If you omit <branch>, what git pushes is regulated by the config option push.default. By default it's matching that means push all the local branches that already have a remote branch with the same name. So if you're on a branch develop with new commits in both develop and master, git will push both.

$ git branch
* develop
  master
$ git push origin
Counting objects: 10, done.
Compressing objects: 100% (4/4), done.
Writing objects: 100% (6/6), 565 bytes, done.
Total 6 (delta 0), reused 0 (delta 0)
To /repo
   364576d..2525509  develop -> develop
   5548fe7..1203e9d  master -> master

Look at the bottom. It pushed master as well. This is good if you use git push as a command to send everything after a work session on multiple branches.

The problem

This can be confusing because it makes push and pull asymmetric. push pushes all matching branches. pull pulls (merges) always just one branch into its own tracking branch. You could end up pushing unwanted changes.

What's a tracking branch

A tracking branch is just a branch that has configuration to let git know its upstream branch, that is, the right remote and remote branch name to push to/pull from. It's done in .git/config in a branch subsection

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

This says that the local branch master should pull from refs/heads/master on origin repository.

How tracking branches are created

A tracking branch is always created if you branch from a remote branch like origin/<branch>.

$ git branch develop origin/develop
Branch develop set up to track remote branch develop from origin.

This is also true when git clone creates the master branch.

Otherwise you can set it explicitly when branching

# git 1.7
$ git branch --set-upstream foo origin/foo
# git 1.8
$ git branch --set-upstream-to=origin/foo foo

or even when pushing with -u option

$ git push -u origin foo

The solution

Push.default to tracking

Change push.default to tracking (upstream from git 1.8) so that push works like pull. Git will now try to push from the current branch to its upstream branch.

$ git config --global push.default tracking
$ git branch
* develop
  master
$ git push origin
Counting objects: 10, done.
Compressing objects: 100% (4/4), done.
Writing objects: 100% (6/6), 565 bytes, done.
Total 6 (delta 0), reused 0 (delta 0)
To /repo
   364576d..2525509  develop -> develop

Only develop this time.

Remember to set up tracking branches for branches you create

Always setup tracking branches when pushing with -u the first time

git push -u origin develop

That's because now if you push a branch with no upstream branch, you'll get an error

fatal: The current branch develop has no upstream branch.
To push the current branch and set the remote as upstream, use

    git push --set-upstream origin develop

Git 2.0

Attention: in git 2.0 push.default will default to simple (much like tracking or upstream).