How to rename a local branch

The initial setup is as follows.

git branch shows that there are two branches main and maincopy. The asterisk denotes that we are currently in maincopy branch.

git status shows it is up to date with origin. git remote -v shows the list of remote repositories. origin is linked to repoone git repository.

~/repoone$ git branch
  main
* maincopy


~/repoone$ git status
On branch maincopy
Your branch is up to date with 'origin/maincopy'.

nothing to commit, working tree clean


~/repoone$ git remote -v
origin  git@github.com:codeversionmaster/repoone.git (fetch)
origin  git@github.com:codeversionmaster/repoone.git (push)
repotwo git@github.com:codeversionmaster/repotwo.git (fetch)
repotwo git@github.com:codeversionmaster/repotwo.git (push)

To rename the branch we are checked in, use git branch -m. Here, we are trying to rename maincopy to newname.

~/repoone$ git branch -m newname

Using git branch, we can see that the branch maincopy gets renamed to newname.

~/repoone$ git branch
  main
* newname

But wait, what is it linked to?

git status shows that it is still linked to origin/maincopy branch, i.e. its name is still maincopy in the remote repository.

~/repoone$ git status
On branch newname
Your branch is up to date with 'origin/maincopy'.

nothing to commit, working tree clean

What to do next depends on if we intend to rename the branch even remotely or push it as a new branch into the remote repository.

If we intend to push it as a new branch, we should first change its upstream link and then push it. We can do this in one step, as shown.

~/repoone$ git push --set-upstream origin newname
Total 0 (delta 0), reused 0 (delta 0), pack-reused 0
remote:
remote: Create a pull request for 'newname' on GitHub by visiting:
remote:      https://github.com/codeversionmaster/repoone/pull/new/newname
remote:
To github.com:codeversionmaster/repoone.git
 * [new branch]      newname -> newname
Branch 'newname' set up to track remote branch 'newname' from 'origin'.

git status would now show that the upstream link is origin/newname and is now present in the remote repository.

~/repoone$ git status
On branch newname
Your branch is up to date with 'origin/newname'.

nothing to commit, working tree clean

Consider this situation where we have two branches main and existingname. We want to rename main to the same name as another existing branch. Here it is existingname.

~/repoone$ git branch
  existingname
* main

In this case, git branch -m would throw an error, as shown.

~/repoone$ git branch -m existingname
fatal: A branch named 'existingname' already exists.

Here, we are checked in existingname branch, and we want to rename main branch as newname.

~/repoone$ git branch
* existingname
  main

Then, we use git branch -m with two arguments, the first argument being the current name and the second argument will be the new name.

As you can see, git branch now shows the name of main branch changed to newname.

~/repoone$ git branch -m main newname

~/repoone$ git branch
  existingname
* newname