[git] Difference between git checkout --track origin/branch and git checkout -b branch origin/branch

Does anybody know the difference between these two commands to switch and track a remote branch?

git checkout -b branch origin/branch
git checkout --track origin/branch

I think both keep track of the remote branch so I can push my changes to the branch on origin, right?

Is there any practical differences??

Thanks!

There is no difference at all!

1) git checkout -b branch origin/branch

If there is no --track and no --no-track, --track is assumed as default. The default can be changed with the setting branch.autosetupmerge.

In effect, 1) behaves like git checkout -b branch --track origin/branch.

2) git checkout --track origin/branch

“As a convenience”, --track without -b implies -b and the argument to -b is guessed to be “branch”. The guessing is driven by the configuration variable remote.origin.fetch.

In effect, 2) behaves like git checkout -b branch --track origin/branch.

As you can see: no difference.

But it gets even better:

3) git checkout branch

is also equivalent to git checkout -b branch --track origin/branch if “branch” does not exist yet but “origin/branch” does¹.

All three commands set the “upstream” of “branch” to be “origin/branch” (or they fail).

Upstream is used as reference point of argument-less git status, git push, git merge and thus git pull (if configured like that (which is the default or almost the default)).

E.g. git status tells you how far behind or ahead you are of upstream, if one is configured.

git push is configured to push the current branch upstream by default² since git 2.0.

^{1 ...and if “origin” is the only remote having “branch”
2 the default (named “simple”) also enforces for both branch names to be equal}

The book seems to indicate that those commands yield the same effect:

The simple case is the example you just saw, running git checkout -b [branch] [remotename]/[branch]. If you have Git version 1.6.2 or later, you can also use the --track shorthand:

$ git checkout --track origin/serverfix 
Branch serverfix set up to track remote branch serverfix from origin. 
Switched to a new branch 'serverfix' 

To set up a local branch with a different name than the remote branch, you can easily use the first version with a different local branch name:

$ git checkout -b sf origin/serverfix

That's particularly handy when your bash or oh-my-zsh git completions are able to pull the origin/serverfix name for you - just append --track (or -t) and you are on your way.

You can't create a new branch with this command

git checkout --track origin/branch

if you have changes that are not staged.

Here is example:

$ git status
On branch master
Your branch is up to date with 'origin/master'.

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

        modified:   src/App.js

no changes added to commit (use "git add" and/or "git commit -a")

// TRY TO CREATE:

$ git checkout --track origin/new-branch
fatal: 'origin/new-branch' is not a commit and a branch 'new-branch' cannot be created from it

However you can easily create a new branch with un-staged changes with git checkout -b command:

$ git checkout -b new-branch
Switched to a new branch 'new-branch'
M       src/App.js