git 上游并跟踪远程分支

Question

I am a bit wondering about the naming "upstream" from git.

If I create a local branch

git checkout -b branch_local

and want to push it somewhere

git push remote_id branch_local:branch_remote

If I look which remote the branch follows:

git branch -vv --all

I see that there is nothing set. If I try:

git pull

I get

If you wish to set tracking information for this branch you can do so with:
git branch --set-upstream-to=<remote>/<branch> branch_local

Why I have to set the "upstream" to get the "downstream" set? Maybe I have not understood if there is an additional downstream setting?

Answer 1

"Upstream" refers to the remote the branch will push and pull by default. This is also called the "remote tracking branch". Sometimes Git will set this for you when you create the branch, but it depends on how you're configured.

In order to ensure the upstream branch is set, use git push -u the first time you push.

git push -u remote branch_local:branch_remote

You can change branch.autoSetupMerge to make Git do this automatically. true will set up tracking when you branch from a remote branch like git co -b foo remote/foo . always will always do the tracking.

Answer 2

You need to tell git to have your local branch track the remote branch. Git being a distributed system, you can make plenty of local branches that don't track any upstream changes.

What you've done is push your local branch to the remote repository, but the local is still not tracking the upstream. There's no "downstream" per se, upstream is the git terminology for the remote repository you're tracking. Once you set that, both push and pull should work (assuming fetch and push urls are the same, but I'm guessing they are at this stage)

Answer 3

Why I have to set the "upstream"

As of git 2.37+, you no longer need to if you set a new configuration parameter:

git config --global push.autoSetupRemote true

With this set, a simple git push in your example above (with branch_local checked out) will push that to the remote ( origin/branch_local ), and set the tracking branch relationship.

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In previous versions of git or without this config, you need to do a more complex push like git push -u origin HEAD , where the -u sets the tracking relationship and the explicit origin and branch are required because the tracking relationship doesn't exist yet.

(assuming that the push.default config is at its default setting of simple )