What is “git remote add …” and “git push origin master”?
Quite often, Git and Rails looks like magic… such as in the first chapter of Rails 3 Tutorial book, it talks about Git:
and it pretty much says “it just works” without saying too much about what they are and start talking about branching. Searching on the net shows that
git remote add is to add a “short name”, such as
origin, and it can be any name as well, which is like an alias to a URL. And
origin is the usual path of where the remote repo points to. (in http://git-scm.com/book/en/Git-Basics-Working-with-Remotes under “Adding Remote Repositories”)
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So why is the URL not
git://email@example.com/peter/first_app.git but in the other syntax — what syntax is it? Why must it end with
.git? I tried not using
.git at the end and it works too. If not
.git, what else can it be? The
firstname.lastname@example.org seems to be a user account on the git server?
Also, why does it need to be so verbose to use
git push origin master? Can’t the default be origin and master? I found that the first time, the
origin master is needed, but after a small edit and commit, then
git push is all it needs (no need
origin master). Can somebody who knows what is going on give some details?
Sometimes it feels like a lot of magic without explanation… and sometimes the person using it is so confident and when asked why, can’t explain it, and respond with something like “that’s the way it is”. Sometimes very practical and pragmatic. It is not bad to be practical, but probably not practical to the point to not know what is going on.
3 Solutions collect form web for “What is “git remote add …” and “git push origin master”?”
git is like UNIX. User friendly but picky about its friends. It’s about as powerful and as user friendly as a shell pipeline.
That being said, once you understand its paradigms and concepts, it has the same zenlike clarity that I’ve come to expect from UNIX command line tools. You should consider taking some time off to read one of the many good git tutorials available online. The Pro Git book is a good place to start.
To answer your first question.
git remote add ...
As you probably know,
gitis a distributed version control system. Most operations are done locally. To communicate with the outside world,
gituses what are called
remotes. These are repositories other than the one on your local disk which you can
pushyour changes into (so that other people can see them) or
pullfrom (so that you can get others changes). The command
git remote add origin email@example.com:peter/first_app.gitcreates a new remote called
firstname.lastname@example.org:peter/first_app.git. Once you do this, in your push commands, you can push to
origininstead of typing out the whole URL.
git push origin master
This is a command that says “push the commits in the local branch named
masterto the remote named
origin“. Once this is executed, all the stuff that you last synchronised with origin will be sent to the remote repository and other people will be able to see them there.
Now about transports (i.e. what
git://) means. Remote repository URLs can be of many types (
https:// etc.). Git simply relies on the authentication mechanism provided by the transport to take care of permissions and stuff. This means that for
file:// URLs, it will be UNIX file permissions, etc. The
git:// scheme is asking git to use its own internal transport protocol, which is optimised for sending git changesets around. As for the exact URL, it’s the way it is because of the way github has set up its
Now the verbosity. The command you’ve typed is the general one. It’s possible to tell git something like “the branch called
master over here is local mirror of the branch called
foo on the remote called
bar“. In git speak, this means that
bar/foo. When you clone for the first time, you will get a branch called
master and a remote called
origin (where you cloned from) with the local master set to track the master on origin. Once this is set up, you can simply say
git push and it’ll do it. The longer command is available in case you need it (e.g.
git push might push to the official public repo and
git push review master can be used to push to a separate remote which your team uses to review code). You can set your branch to be a tracking branch using the
--set-upstream option of the
git branch command.
I’ve felt that git (unlike most other apps I’ve used) is better understood from the inside out. Once you understand how data is stored and maintained inside the repository, the commands and what they do become crystal clear. I do agree with you that there’s some elitism amongst many
git users but I also found that with UNIX users once upon a time, and it was worth ploughing past them to learn the system. Good luck!
Update: note that the currently accepted answer perpetuates a common misunderstanding about the behaviour of
git push, which hasn’t been corrected despite a comment pointing it out.
Your summary of what remotes are – like a nickname for the URL of a repository – is correct.
So why does the URL not git://email@example.com/peter/first_app.git but in the other syntax — what syntax is it? Why must it end with .git? I tried not using .git at the end and it works too. If not .git, what else can it be? The git at the beginner seems to be a user account on the git server?
The two URLs that you’ve mentioned indicate that two different transport protocols should be used. The one beginning with
git:// is for the git protocol, which is usually only used for read-only access to repositories. The other one,
firstname.lastname@example.org:peter/first_app.git, is one of the different ways of specifying access to a repository over SSH – this is the “scp-style syntax” described in the documentation. That the username in the scp-style syntax is
git is because of the way that GitHub deals with identifying users – essentially that username is ignored, and the user is identified based on the SSH key-pair that they used to authenticate.
As for the verbosity of
git push origin master, you’ve noticed that after the first push, you can then just do
git push. This is because of a series of difficult-to-remember-but-generally-helpful defaults 🙂
- If no remote is specified, the remote configured for the current branch (in
remote.master.urlin your case) is used. If that’s not set up, then
- If there’s no “refspec” (e.g.
master:my-experiment, etc.) specified, then git defaults to pushing every local branch that has the same name as a branch on the remote. If you just have a branch called
masterin common between your repository and the remote one, that’ll be the same as pushing your
masterto the remote
Personally, since I tend to have many topic branches (and often several remotes) I always use the form:
git push origin master
… to avoid accidentally pushing other branches.
In reply to your comments on one of the other answers, it sounds to me as if are learning about git in a top-down way very effectively – you’ve discovered that the defaults work, and your question is asking about why 😉 To be more serious, git can be used essentially as simply as SVN, but knowing a bit about remotes and branches means you can use it much more flexibily and this can really change the way you work for the better. Your remark about a semester course makes me think of something Scott Chacon said in a podcast interview – students are taught about all kinds of basic tools in computer science and software engineering, but very rarely version control. Distributed version control systems such as git and Mercurial are now so important, and so flexible, that it would be worth teaching courses on them to give people a good grounding.
My view is that with
git, this learning curve is absolutely worth it – working with lots of topic branches, merging them easily, and pushing and pulling them about between different repositories is fantastically useful once you become confident with the system. It’s just unfortunate that:
- The primary documentation for git is so hard to parse for newcomers. (Although I’d argue that if you Google for almost any git question, helpful tutorial material (or Stack Overflow answers :)) come up nowadays.)
- There are a few odd behaviours in git that are hard to change now because many scripts may rely on them, but are confusing to people.
.gitat the end of the repository name is just a convention. Typically, on git servers repositories are kept in directories named
project.git. The git client and protocol honours this convention by testing for
git://email@example.com/peter/first_app.gitis not a valid git url. git repositories can be identified and accessed via various url schemes specified here.
sshurl mentioned on that page.
gitis flexible. It allows you to track your local branch against almost any branch of any repository. While
master(your local default branch) tracking
origin/master(the remote default branch) is a popular situation, it is not universal. Many a times you may not want to do that. This is why the first
git pushis so verbose. It tells git what to do with the local
masterbranch when you do a
git pullor a
The default for
git pullis to work with the current branch’s remote. This is a better default than origin master. The way git push determines this is explained here.
git is fairly elegant and comprehensible but there is a learning curve to walk through.