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[MUSIC]

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Collaborating with other developers is
one of the biggest reasons to use git.

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And to do that,

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you need to be able to bring changes from
their git repositories into your repo.

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You also need to be able to share
changes from your repo to their repos.

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You do that using remote branches.

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A remote branch is like a local branch,
but

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it points to the commit that
a branch in a remote repo is at.

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You can update a local branch with
commits from a remote repository by

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merging a remote branch
into a local branch.

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Normally, remote branches are used with
a repo on a different machine, but

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they'll also work if we clone
a repo to a second local directory.

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This will also let us see the effects on
both sides as we push and pull commits.

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So let's Let's do a local clone.

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We'll have our original repo
act as the remote repo, and

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our clone act as the local repo.

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I'm in the original repo right now, so

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I'll change to the directory
that contains it with cd ..

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Remember that the .., stands for
the parent directory.

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We clone the repo with
the git clone command.

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In place of a URL, we'll have it
clone from the decoder directory.

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We'll set up the clone in
the decoder local directory.

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Let's change into the directory for
our so-called local repo, the clone.

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As always, when you clone a repo,

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the original repo is set up as
a remote repo named origin.

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We can see this if we run
the git remote command.

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If we run the git branch command,

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we'll see that git has also
set up a master branch for us.

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That's the only branch visible for now.

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There's no sign of the add letters
branch for the remote repo.

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If we run git log,

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we'll see all the commits from the master
branch were cloned along with repo.

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If we run git status,
we'll see something new.

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At the top it says on
branch master as usual, but

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then below that it says your branch
is up to date with origin/master.

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Origin master is a remote branch.

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You can tell a remote branch
name when you see one,

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because it always has the remote repo
name, a slash, and then the branch name.

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Let's try using the remote branch to
bring a commit from the remote repo to

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the local repo.

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I'll be using the fetch and
merge subcommands for this.

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I'll do this twice,
once to give you an overview, and

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then again explaining
every step more carefully.

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It'll involve quite a lot of steps, but

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this way you'll know
exactly what's happening.

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In an upcoming video, I'll show you
a shortcut to do the same thing.

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So first we need to make
a commit in the original repo,

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the one we're treating as a remote repo.

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I'll change into that
directory with cd../decoder.

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This changes up to the parent directory,
and

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then immediately changes
into the decoder directory.

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Let's make sure the master branch is
checked out, git checkout master.

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Now let's edit the decoder.rb file,
and we'll add a new letter conversion.

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We'll say number 26 gets
converted to the letter Z.

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Let's save this, and now we'll
stage the file, git add decoder.rb.

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And we'll commit it,
git commit-m 'Add Z conversion'.

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Now we have a new commit on the master
branch and our remote repo.

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Let's got to our local repo and use the
remote branch to copy that commit over.

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I need to change to the clone's
directory with cd../decoder-local.

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Again, that will change to
the parent directory, and

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into the decoder local subdirectory.

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To connect to the remote repo and

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update our remote branches in this local
repo, we use the git fetch command.

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We need to give git fetch an argument with
the name of the remote repo to connect to,

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so we'll say git fetch origin.

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Now, if I run git status again,
You'll see that

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the master local branch is out of sync
with the origin master remote branch.

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This is because the origin master
branch has been updated, but

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the master branch hasn't.

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We can update the local master branch by
merging the remote origin master branch

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into it.

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To do that, we use the get merge command,
just as we would with any other branch.

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Git merge origin/master.

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This will merge the remote origin master
branch into the local master branch.

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If we run git log now,
we'll see the commit from our remote repo,

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Add Z conversion.

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And if we look at the code for
the decoder.rb file,

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we'll see the code from that commit.

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I'll just use the cat
program to show this.

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You can see the code to convert
the number 26 to the letter Z here.

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And this is in our local repository.

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Now let me do this again, but explaining
everything in a little more detail.

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I'll need to make another
commit in the remote repo.

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I'll change into that directory,
with cd../decoder.

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Let's add another
conversion to decoder.rb.

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Here in my editor I'm still
editing the remote repo.

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So here in the decoder.rb, I'll add
another conversion for the letter Y.

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Let me save this, and
stage it here in the remote repo.

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And then commit it.

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git commit -m 'Add Y conversion.

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Now, I'll follow the same
process as before.

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I'll go to my local repo and use the
remote branch to copy that commit over.

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I'll change to the clones directory,
cd ../decoder-local/.

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Now, at this point,

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there's no indication in the local repo
that the remote repo has been updated.

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We'll see that if we run git status.

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It says our branch is up to date with
the remote origin/master branch.

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And that's true, but

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only because our remote branch is out
of sync with the actual remote repo.

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To connect to the remote repo and update
our remote branches in this local repo,

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we need to use the git
fetch command again.

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Git fetch origin.

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Git fetch will copy overall the commits
the remote repo has that our local repo

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doesn't.

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Those are the objects you see
at copying over in the output.

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Git fetch also updates the remote
branches in your local repo.

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Previously the remote origin master
branch was pointing at the same commit

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as our local master branch.

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That's the first commit SHA that
you see in the output here.

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That's why the git status command
reported that master was up-to-date with

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origin/master.

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But git fetch updates the origin/master
remote branch to point to the same commit

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as the master branch in the remote repo.

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That's the second commit SHA
that you see in the output here.

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Now if we rerun git status, it'll show
that the local master branch is behind

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the remote origin master
branch by one commit.

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We update master by merging origin
master into it, git merge origin/master.

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You can see that it updates the local
master branch to the same commit that was

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retrieved by git fetch.

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And again, if we run git log
on the local master branch,

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it will show the new commit
merged in from the remote branch.

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And if we check the file contents,
cat decoder.rb,

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we'll see that they've
been updated as well.

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So now we know how to fetch
commits from a remote branch and

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merge them into a local branch.

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But the master branch was
already set up for us.

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How do you set up new local
branches to merge into?

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We'll look at that in the next video.