Git rename branch

I have a local branch with a long name so I want to rename it shorter.

Rename a local branch by this command

git branch -m oldName newName

Update:
After I rename the local branch and try to push code, I got this error:

fatal: The upstream branch of your current branch does not match the name of your current branch. To push to the upstream branch on the remote, use git push origin HEAD:oldName To push to the branch of the same name on the remote, use git push origin HEAD 

So I followed the advice and git push origin HEAD:oldName then it works like a charm.