Git doesn't have a central server like Subversion. All of the commands so far have been done locally, just updating a local database. To collaborate with other developers in Git, you have to put all that data on a server that the other developers have access to. The way Git does this is to syncronize your data with another repository. There is no real difference between a server and a client - a Git repository is a Git repository and you can syncronize between any two easily.
Once you have a Git repository, either one that you set up on your own server, or one hosted someplace like GitHub, you can tell Git to either push any data that you have that is not in the remote repository up, or you can ask Git to fetch differences down from the other repo.
You can do this any time you are online, it does not have to correspond
with a commit or anything else. Generally you will do a
number of commits locally, then fetch data from the online shared repository
you cloned the project from to get up to date, merge any new work into the
stuff you did, then push your changes back up.
In a nutshell you can update your project with git fetch
and share your changes with git push. You can manage your
remote repositories with git remote.
Unline centralized version control systems that have a client that is very different from a server, Git repositories are all basically equal and you simply syncronize between them. This makes it easy to have more than one remote repository - you can have some that you have read-only access to and others that you can write to as well.
So that you don't have to use the full URL of a remote repository every
time you want to syncronize with it, Git stores an alias or nickname for
each remote repository URL you are interested in. You use the
git remote command to manage this list of remote repos that
you care about.
Without any arguments, Git will simply show you the remote repository
aliases that it has stored. By default, if you cloned the project (as
opposed to creating a new one locally), Git will automatically add the
URL of the repository that you cloned from under the name 'origin'. If
you run the command with the -v option, you can see the
actual URL for each alias.
$ git remote origin $ git remote -v origin git@github.com:schacon/git-reference.git (fetch) origin git@github.com:schacon/git-reference.git (push)
You see the URL there twice because Git allows you to have different push and fetch URLs for each remote in case you want to use different protocols for reads and writes.
If you want to share a locally created repository, or you want to take
contributions from someone elses repository - if you want to interact in
any way with a new repository, it's generally easiest to add it as a remote.
You do that by running git remote add [alias] [url]. That
adds [url] under a local remote named [alias].
For example, if we want to share our Hello World program with the world, we can create a new repository on a server (I'll use GitHub as an example), which should give you a URL, in this case "git@github.com:schacon/hw.git". To add that to our project so we can push to it and fetch updates from it we would do this:
$ git remote $ git remote add github git@github.com:schacon/hw.git $ git remote -v github git@github.com:schacon/hw.git (fetch) github git@github.com:schacon/hw.git (push)
Like the branch naming, remote alias names are arbitrary - just as 'master'
has no special meaning but is widely used because git init
sets it up by default, 'origin' is often used as a remote name because
git clone sets it up by default as the cloned-from URL. In
this case I've decided to name my remote 'github', but I could have really
named it just about anything.
Git addeth and Git taketh away. If you need to remove a remote - you are
not using it anymore, the project is gone, etc - you can remove it with
git remote rm [alias].
$ git remote -v github git@github.com:schacon/hw.git (fetch) github git@github.com:schacon/hw.git (push) $ git remote add origin git://github.com/pjhyett/hw.git $ git remote -v github git@github.com:schacon/hw.git (fetch) github git@github.com:schacon/hw.git (push) origin git://github.com/pjhyett/hw.git (fetch) origin git://github.com/pjhyett/hw.git (push) $ git remote rm origin $ git remote -v github git@github.com:schacon/hw.git (fetch) github git@github.com:schacon/hw.git (push)
In a nutshell with git remote you can list our
remote repositories and whatever URL
that repository is using. You can use git remote add to
add new remotes and git remote rm to delete existing ones.