git-reference/remotes/index.html

---
layout: reference
---

<div class="box">
  <h2>
    <span class="docs">
      <a target="new" href="http://progit.org/book/ch2-5.html">book</a>
    </span>
    Sharing and Updating Projects
  </h2>
  <div class="block">
    <p>
    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.
    </p>

    <p>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.
    </p>

    <p>You can do this any time you are online, it does not have to correspond
    with a <code>commit</code> 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.</p>

    <p class="nutshell">
    <b>In a nutshell</b> you can update your project with <code>git fetch</code>
    and share your changes with <code>git push</code>. You can manage your
    remote repositories with <code>git remote</code>.
    </p>
  </div>
</div>

<div class="box">
  <h2>
    <span class="docs">
      <a target="new" href="http://www.kernel.org/pub/software/scm/git/docs/git-remote.html">docs</a> &nbsp;
      <a target="new" href="http://progit.org/book/ch2-5.html#showing_your_remotes">book</a>
    </span>
    <a name="push">git remote</a>
    <span class="desc">list, add and delete remote repository aliases</span>
  </h2>

  <div class="block">

    <p>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.</p>

    <p>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
    <code>git remote</code> command to manage this list of remote repos that
    you care about.</p>

    <h4>
      git remote
      <small>list your remote aliases</small>
    </h4>

    <p>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 <code>-v</code> option, you can see the
    actual URL for each alias.</p>

<pre>
<b>$ git remote</b>
origin
<b>$ git remote -v</b>
origin	git@github.com:schacon/git-reference.git (fetch)
origin	git@github.com:schacon/git-reference.git (push)
</pre>

    <p>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.</p>

    <h4>
      git remote add
      <small>add a new remote repository of your project</small>
    </h4>

    <p>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 <code>git remote add [alias] [url]</code>.  That
    adds <code>[url]</code> under a local remote named <code>[alias]</code>.</p>

    <p>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:</p>

<pre>
<b>$ git remote</b>
<b>$ git remote add github git@github.com:schacon/hw.git</b>
<b>$ git remote -v</b>
github	git@github.com:schacon/hw.git (fetch)
github	git@github.com:schacon/hw.git (push)
</pre>

    <p>Like the branch naming, remote alias names are arbitrary - just as 'master'
    has no special meaning but is widely used because <code>git init</code>
    sets it up by default, 'origin' is often used as a remote name because
    <code>git clone</code> 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.
    </p>

    <h4>
      git remote rm
      <small>removing an existing remote alias</small>
    </h4>

    <p>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
    <code>git remote rm [alias]</code>.</p>

<pre>
<b>$ git remote -v</b>
github	git@github.com:schacon/hw.git (fetch)
github	git@github.com:schacon/hw.git (push)
<b>$ git remote add origin git://github.com/pjhyett/hw.git</b>
<b>$ git remote -v</b>
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)
<b>$ git remote rm origin</b>
<b>$ git remote -v</b>
github	git@github.com:schacon/hw.git (fetch)
github	git@github.com:schacon/hw.git (push)
</pre>

    <p class="nutshell">
    <b>In a nutshell</b> with <code>git remote</code> you can list our
    remote repositories and whatever URL
    that repository is using.  You can use <code>git remote add</code> to
    add new remotes and <code>git remote rm</code> to delete existing ones.
    </p>

  </div>
</div>

<div class="box">
  <h2>
    <span class="docs">
      <a target="new" href="http://www.kernel.org/pub/software/scm/git/docs/git-fetch.html">docs</a> &nbsp;
      <a target="new" href="http://progit.org/book/ch2-5.html#fetching_and_pulling_from_your_remotes">book</a>
    </span>
    <a name="fetch">git fetch</a>
    <span class="desc">download new branches and data from a remote repository</span>
  </h2>

  <br/>

  <h2>
    <span class="docs">
      <a target="new" href="http://www.kernel.org/pub/software/scm/git/docs/git-pull.html">docs</a> &nbsp;
      <a target="new" href="http://progit.org/book/">book</a>
    </span>
    <a name="pull">git pull</a>
    <span class="desc">fetch from a remote repo and try to merge into the current branch</span>
  </h2>

  <div class="block">

    <p>Git has two commands to update itself from a remote repository.
    <code>git fetch</code> will syncronize you with another repo, pulling down any data
    that you do not have locally and giving you bookmarks to where each branch on
    that remote was when you syncronized.  These are called "remote branches" and are
    identical to local branches except that Git will not allow you to check them out -
    however, you can merge from them, diff them to other branches, run history logs on
    them, etc.  You do all of that stuff locally after you syncronize.
    </p>

    <p>The second command that will fetch down new data from a remote server is
    <code>git pull</code>.  This command will basically run a <code>git fetch</code>
    immediately follwed by a <code>git merge</code> of the branch on that remote
    that is tracked by whatever branch you are currently in.  I personally don't much
    like this command - I prefer running <code>fetch</code> and <code>merge</code>
    seperately.  Less magic, less problems.  However, if you like this idea, you
    can read about it in more detail in the.
    <a target="new" href="http://www.kernel.org/pub/software/scm/git/docs/git-pull.html">official docs</a>.
    </p>

    <p>Assuming you have a remote all set up and you want to pull in updates, you
    would first run <code>git fetch [alias]</code> to tell Git to fetch down all the
    data it has that you do not, then you would run <code>git merge [alias]/[branch]</code>
    to merge into your current branch anything new you see on the server
    (like if someone else has pushed in the meantime). So, if I were working on my
    Hello World project with several other people and I wanted to bring in any changes
    that had been pushed since I last connected, I would do something like this:</p>

<pre>
<b>$ git fetch github</b>
remote: Counting objects: 4006, done.
remote: Compressing objects: 100% (1322/1322), done.
remote: Total 2783 (delta 1526), reused 2587 (delta 1387)
Receiving objects: 100% (2783/2783), 1.23 MiB | 10 KiB/s, done.
Resolving deltas: 100% (1526/1526), completed with 387 local objects.
From github.com:schacon/hw
   8e29b09..c7c5a10  master     -> github/master
   0709fdc..d4ccf73  c-langs    -> github/c-langs
   6684f82..ae06d2b  java       -> github/java
 * [new branch]      ada        -> github/ada
 * [new branch]      lisp       -> github/lisp
</pre>

    <p>I can see that since the last time I synchronized with this remote, five branches
    have been added or updated.  The 'ada' and 'lisp' branches are new, where the
    'master', 'c-langs' and 'java' branches have been updated.  In this case, my team
    is pushing proposed updates to remote branches for review before they're merged
    into 'master'.
    </p>

    <p>You can see the mapping that Git makes.  The 'master' branch on the remote
    repository becomes a branch named 'github/master' locally.  That way now I can
    merge the 'master' branch on that remote into my local 'master' branch by running
    <code>git merge github/master</code>.  Or, I can see what new commits are on that
    branch by running <code>git log github/master ^master</code>.  If your remote
    is named 'origin' it would be <code>origin/master</code> instead.  Almost any
    command you would run using local branches you can use remote branches with too.
    </p>

    <p>If you have more than one remote repository, you can either fetch from specific
    ones by running <code>git fetch [alias]</code> or you can tell Git to syncronize
    with all of your remotes by running <code>git fetch --all</code>.

    <p class="nutshell">
    <b>In a nutshell</b> you run <code>git fetch [alias]</code> to syncronize your
    repository with a remote repository, fetching all the data it has that you do
    not into branch references locally for merging and whatnot.
    </p>

  </div>

</div>

<div class="box">
  <h2>
    <span class="docs">
      <a target="new" href="http://www.kernel.org/pub/software/scm/git/docs/git-push.html">docs</a> &nbsp;
      <a target="new" href="http://progit.org/book/ch2-5.html#pushing_to_your_remotes">book</a>
    </span>
    <a name="push">git push</a>
    <span class="desc">push your new branches and data to a remote repository</span>
  </h2>

  <div class="block">
    <p>To share the cool commits you've done with others, you need to push your
    changes to the remote repository. To do this, you run
    <code>git push [alias] [branch]</code> which will attempt to make your [branch]
    the new [branch] on the [alias] remote. Let's try it by initially pushing
    our 'master' branch to the new 'github' remote we created earlier.</p>

<pre>
<b>$ git push github master</b>
Counting objects: 25, done.
Delta compression using up to 2 threads.
Compressing objects: 100% (25/25), done.
Writing objects: 100% (25/25), 2.43 KiB, done.
Total 25 (delta 4), reused 0 (delta 0)
To git@github.com:schacon/hw.git
 * [new branch]      master -> master
</pre>

    <p>Pretty easy. Now if someone clones that repository they will get exactly
    what I have committed and all of it's history.</p>

    <p>What if I have a topic branch like the 'erlang' branch we created earlier
    and I just want to share that?  You can just push that branch instead.

<pre>
<b>$ git push github erlang</b>
Counting objects: 7, done.
Delta compression using up to 2 threads.
Compressing objects: 100% (6/6), done.
Writing objects: 100% (6/6), 652 bytes, done.
Total 6 (delta 1), reused 0 (delta 0)
To git@github.com:schacon/hw.git
 * [new branch]      erlang -> erlang
</pre>

    <p>Now when people clone or fetch from that repository, they'll get a 'erlang'
    branch they can look at and merge from. You can push any branch to any
    remote repository that you have write access to in this way. If your branch
    is already on the server, it will try to update it, if it is not, Git will
    add it.</p>

    <p>The last major issue you run into with pushing to remote branches is the
    case of someone pushing in the meantime.  If you and another developer clone
    at the same time, you both do commits, then she pushes and then you try to
    push, Git will by default not allow you to overwrite her changes.  Instead,
    it basically runs <code>git log</code> on the branch you're trying to push and
    makes sure it can see the current tip of the servers branch in your pushes
    history.  If it can't see what is on the server in your history, it concludes
    that you are out of date and will reject your push.  You will rightly have to
    fetch, merge then push again - which makes sure you take her changes into
    account.</p>

    <p>This is what happens when you try to push a branch to a remote branch
    that has been updated in the meantime:</p>

<pre>
<b>$ git push github master</b>
To git@github.com:schacon/hw.git
 ! [rejected]        master -> master (non-fast-forward)
error: failed to push some refs to 'git@github.com:schacon/hw.git'
To prevent you from losing history, non-fast-forward updates were rejected
Merge the remote changes before pushing again.  See the 'Note about
fast-forwards' section of 'git push --help' for details.
</pre>

    <p>You can fix this by running <code>git fetch github; git merge github/master</code>
    and then pushing again.

    <p class="nutshell">
    <b>In a nutshell</b> you run <code>git push [alias] [branch]</code> to update a
    remote repository with the changes you've made locally.  It will take what your
    [branch] looks like and push it to be [branch] on the remote, if possible.  If
    someone else has pushed since you last fetched and merged, the Git server will
    deny your push until you are up to date.
    </p>

  </div>
</div>

<p><a href="/inspect">On to Inspection and Comparison &#187;</a></p>