Cloning (downloading) a Repository

Cloning (downloading) a Repository

You’ve now learned how to push (upload) a copy of your local repository to the cloud (e.g. GitHub). The next question is how can we download a repository from the cloud?

Why would we want to do this? Well, one good reason may be that you may want to have a copy of your repository on both your laptop and on your desktop, or on your work PC and on your home PC. Downloading your repository to another computer allows you to split your work across more than one machine, all the while using your cloud (GitHub) repository to keep everything in sync.

To download a Git repository to a new computer, use the git clone command. As we are not going to use a new computer in this workshop, we will fake a new computer by downloading to a new directory.

First, change into your home directory by typing

cd

Now, create and change into a new directory called tmpdir using

mkdir tmpdir
cd tmpdir

To clone your repository, type

git clone https://github.com/USERNAME/versioned_dir.git

where USERNAME is your GitHub username, e.g. I would write

git clone https://github.com/chryswoods/versioned_dir.git

This will output something like

Cloning into 'versioned_dir'...
remote: Counting objects: 28, done.
remote: Compressing objects: 100% (21/21), done.
remote: Total 28 (delta 2), reused 28 (delta 2), pack-reused 0
Unpacking objects: 100% (28/28), done.
Checking connectivity... done

This shows that Git has downloaded the versioned_dir git repository and unpacked into a new directory, also called versioned_dir.

You can confirm this by typing

ls versioned_dir

You should see that this is a copy of your other versioned_dir directory.

Change into this new versioned_dir directory using

cd versioned_dir

Get the status of the clone using git status. You should see that you have cloned a clean version of the master branch, e.g.

# On branch master
nothing to commit, working directory clean

Note that because GitHub only has a copy of your master branch, your cloned repository also only has a master branch. You can confirm this by running git branch and looking at the output. If you have lots of branches on GitHub, then all of these will be downloaded in the clone. This is because git clone creates a complete and identical clone of the GitHub repository.

Making a change

You should now have two copies of your versioned_dir directory;

  • The “original”, which is versioned_dir
  • The “clone”, which is tmpdir/versioned_dir

Edit the README.MD in the clone directory, e.g.

nano README.MD

Edit this file so that it reads

# Hello GitHub

This is a README.MD file that will be used to describe this
repository on GitHub

This is	an extra line of text added to the copy	
of README.MD in the cloned repository

Save the file and exit from nano, and then check git status to see that Git knows that you have changed README.MD.

Commit the change and push this up to the cloud repository. Remember to add a useful commit message.

git commit -a
git push

Take a look at your repository on github.com using your webbrowser. You should see that you have pushed up a change from the “cloned” repository.

Now, change directory into the original versioned_dir, e.g. via

cd ../../versioned_dir

Take a look at README.MD in this original versioned_dir directory. You should see that this file has not been changed - it doesn’t include the new line of text that was added via the “cloned” directory.

To get this line of text, we need to sync our local original versioned_dir with the cloud GitHub repository. In the last page, syncing was always pushing changes from the local directory to the cloud, and used git push. It should be no surprise that pulling changes from the cloud to the local directory uses git pull.

Type

git pull

You should see output that is similar to

remote: Counting objects: 3, done.
remote: Compressing objects: 100% (3/3), done.
remote: Total 3 (delta 0), reused 3 (delta 0), pack-reused 0
Unpacking objects: 100% (3/3), done.
From http://github.com/chryswoods/versioned_dir
   e1dd8ff..46fefdd  master     -> origin/master
Updating e1dd8ff..46fefdd
Fast-forward
 README.MD | 2 ++
 1 file changed, 2 insertions(+)

This shows that Git has recognised that the GitHub cloud repository has newer versions than the local repository. Git downloads these changes and then applies them to the files in your local repository. In this case, the changes only affected README.MD, and just involved inserting two lines (2 insertions).

Take a look at README.MD. You should see that it now has the new lines that were added from the “cloned” repository. If you run git status you should see that the current working directory is clean.

Workflow

The “normal” workflow when using Git on your own is;

  • git pull new versions from the cloud repository
  • Now make changes to your files as you would normally.
  • git commit -a your changes.
  • git status to ensure that your working directory is clean.
  • git push to push your changes back up to the cloud.

Exercise

Make some changes in your “original” versioned_dir directory, e.g. edit README.MD, add new files or add new subdirectories.

Use git commit -a and git push to commit your changes, and then push them to your cloud repository.

Then, change directory into your “cloned” versioned_dir, e.g. via cd ../tmpdir/versioned_dir. Use git pull to pull the latest version from the cloud. Check that the changes you made to the “original” versioned_dir have been copied to the “cloned” versioned_dir.

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