667
edits
Changes
→Step 4: Syncing Changes Between Repositories
</pre>
===Step 4: Syncing Pushing Changes Between to Remote Repositories===
Let's make a change to our cloned Spoon-Knife repo, then sync that change with our remote Github forked repository. We start by making a change locally.
My full commit is visible at https://github.com/humphd/Spoon-Knife/commit/57f7209f758c4ba32be537434196b9168b2d53dc
===Step 5: Pulling and Fetching Changes from Remote Repositories===
Just as we can send changes (i.e., commits) to a remote repository that we own (or have been granted write permission), we can can '''pull''' changes from any public, cloned repo, whether we own it or not: we don't need explicit permission.
Earlier we '''forked''' the [https://github.com/twbs/bootstrap Bootstrap] repo. Let's '''clone''' it locally now, and setup our '''origin''' and '''upstream''' remotes:
<pre>
$ git clone git@github.com:humphd/bootstrap.git
Cloning into 'bootstrap'...
remote: Counting objects: 103419, done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 103419 (delta 0), reused 0 (delta 0), pack-reused 103417
Receiving objects: 100% (103419/103419), 92.52 MiB | 1.40 MiB/s, done.
Resolving deltas: 100% (69071/69071), done.
$ cd bootstrap
$ git remote add upstream https://github.com/twbs/bootstrap.git
$ git remote -v
origin git@github.com:humphd/bootstrap.git (fetch)
origin git@github.com:humphd/bootstrap.git (push)
upstream https://github.com/twbs/bootstrap.git (fetch)
upstream https://github.com/twbs/bootstrap.git (push)
</pre>
If we wanted to update our local clone to be in sync with the '''upstream''' Bootstrap repo, we'd do this:
<pre>
$ git pull upstream v4-dev
From https://github.com/twbs/bootstrap
* branch v4-dev -> FETCH_HEAD
Already up-to-date.
</pre>
Here we've asked git to '''pull''' all commits on the <code>v4-dev</code> '''branch'''. We'll be discussing '''branches''' in detail in the next walk-through, but for now a branch is a line of commits with a friendly name: it's easier to remember <code>v4-dev</code> than <code>b47c252ee13c536205105dcb16029021118f989c</code>! Git responds by telling us that we're '''Already up-to-date''', which means there's nothing new. If you wait for a while and try that again, you'll see that new changes are available, and will get added to our local repo.
We should say something about git's <code>pull</code> command vs. <code>fetch</code>. When git downloads all new commits from a remote repo, we call that a <code>fetch</code>. You can do it yourself:
<pre>
$ git fetch upstream
</pre>
In this case nothing got downloaded. A <code>fetch</code> is '''always''' safe to do, because it just downloads any new commits, but doesn't update your current work yet--you do that using git's <code>merge</code>. We'll discuss <code>merge</code> at length in the next walk-through, but for now it's useful to understand that a merge connects two (or more) existing commits. When you do a <code>git pull</code>, it combines a <code>git fetch</code> and <code>git merge</code> in a single operation.
===Step 6: Creating Pull Requests (PRs)===
So far we've learned how to '''pull''' and '''fetch''' changes from remote repositories, and also how to '''push''' changes to remote repositories we own. This leaves the question of how to share changes with repositories that you don't own. How does one contribute a bug fix to a project for which they don't have write permissions?
Github's answer to this question is the [https://help.github.com/articles/about-pull-requests/ Pull Request], also known as a '''PR'''. A pull request is a commit (or set of commits) you've made that you want to have pulled into an upstream repository. A pull request provides code changes (commits), but also a forum for discussion, code review, and evolution of the changes.
We've been discussing Bootstrap, so let's look at [https://github.com/twbs/bootstrap/pull/17821 a real pull request] (you can see all [https://github.com/twbs/bootstrap/pulls current pull requests as well]). This pull request was opened in October 2015, and provides a fix for [https://github.com/twbs/bootstrap/issues/17811 this issue] (note the presence of <code>fixes #17811</code>). Within this PR we can see a few things:
* '''[https://github.com/twbs/bootstrap/pull/17821 Conversation]''' - a running discussion between developers about this change, including code review, new commits, and a history of different status and label changes
* '''[https://github.com/twbs/bootstrap/pull/17821/commits Commits]''' - a list of all the commits in this PR. NOTE: you can always add more commits to a PR by pushing new commits to your remote, which we'll discuss in the next walk-through
* '''[https://github.com/twbs/bootstrap/pull/17821/files Files changed]''' - a complete DIFF of all the file changes, as well as specific code review comments on particular lines
** Remotes
