why "git fetch origin bugfix" does not work?

Question

I tried this to fetch a remote branch:

% git fetch origin bugfix

And the console tells me:

From github.com:*****/sdn-prjkt
 * branch            bugfix     -> FETCH_HEAD

Looks like it's fetched. But when I try to list all branches but it's not fetched to local:

% git branch
* main

Still in remote:

% git branch -a
* main
  remotes/origin/HEAD -> origin/main
  remotes/origin/bugfix
  remotes/origin/main

May I know why?

Answer 1

Your branches are yours . The git fetch command obtains commits: you and they ¹ share the commits, which are all always, completely read-only, so they can't change yours and you can't change theirs and therefore it's completely safe to share them. But git fetch does not get any branches .

Instead, your Git remembers their branches using your remote-tracking names . You can list these with git branch -r , or with git branch -a as you just did. The remote-tracking names for the remote named origin are spelled with origin/ in front of them: origin/main , origin/bugfix , and so on.

For no good reason, git branch -r shows these as origin/bugfix but git branch -a shows them as remotes/origin/bugfix . The fact is that each of these names is shortened:

• your branch name main is short for refs/heads/main ;
• your remote-tracking name origin/main is short for refs/remotes/origin/main ;

and so on. Git drops refs/heads/ from branch names when shortening them, drops refs/tags/ from tag names when shortening tag names, and drops refs/remotes/ , or sometimes just refs/ , from remote-tracking names when shortening those.

If you would like to have your own branch name , you simply tell Git: Create, for me, a new branch name bugfix , using the same commit I just saw on their Git that they call bugfix , which I call origin/bugfix .

The long form of this command is:

git branch --track bugfix origin/bugfix

after which git checkout bugfix or git switch bugfix finds that you have a branch named bugfix , and switches to that branch and extracts that branch's tip commit as the current commit. (Remember, each commit holds a full snapshot of every file—though in a special, read-only, Git-only, compressed and de-duplicated form—so for you to use a commit, Git has to extract its files .)

There's a shortcut, though:

git checkout bugfix

or:

git switch bugfix

starts out ready to complain that, hey, there's no branch named bugfix , we can't possibly do that—but then, because you didn't say --no-guess , they use what Git used to call DWIM mode to guess whether they should create a branch named bugfix .

To guess, they look at all your remote-tracking names, as if you'd run git branch -r . If there's exactly one that looks right—such as origin/bugfix —they'll automatically do that git branch command for you. ² Then, now that you have a bugfix , they can switch to it successfully. You'll get a message about having switched to a newly created branch.

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¹ You here means your Git software, running on your computer, operating on your repository . They means their Git software, running on their computer, operating on their repository . Note that there are two independent Git repositories here. The git fetch operation means Call up their Git and get any commits they have, that I don't, that they are willing to hand over. Then, based on what you saw for their branch names, create or update my remote-tracking names to match their branch names.

² Whether they use git branch --track or git branch --no-track is actually configurable, but the default is to use --track . Be careful with this verb track: Git overuses it a lot, so when you see it elsewhere in Git, it might refer to this, but it might refer to something else.