GitHub, even with it's flaws, is the primary website for
sharing and uploading your code with git. They also have a great
student pack which gives you all kinds of
great benefits.
Using the + button in the top right corner or the webpage, choose "New Repository". Pick a name and optionally a description. For this tutorial, we will not be using a pre-provided README, .gitignore, or license. We may these at future UUG sessions.
Once you create the repository you will get a page with a bunch of commands
that GitHub wants you to run. Select the HTTPS button towards the top of this
guide, and notice the line starting with git remote add origin. You don't need
to do anything with this now. Just keep the page open.
First, we will create a directory to use for this tutorial.
mkdir -p ~/UUG/git_tutorial && cd $_
If we try to use a git command here, we will get an error
git commit -am "Test commit"
Notice that you got an error when you tried to do this! You cannot create a commit in git without that directory being a part of a git repository.
So let's initialize your git repository.
git init
Now we will use that command from earlier
git add remote origin https://github.com/YOURUSERNAME/REPONAME.git
This has created a .git folder, with all the information about your repository.
ls -a
ls .git
By default, git will have your name and email configured to be your login
name@hostname. This is nice in some ways, but probably not your actual
email address. Let's fix this.
git config --global user.name "Your Name"
git config --global user.email "[email protected]"
Now git will always know who you are, and this information will be in all
your commits.
Commits are basically a record of changes to your directory. Each time you
make a change, you need to tell git to create a new record. You do this
with the commit command.
Before you commit, you have to make a change to the directory. Let's create a file
vim README.txt
Now that we have modified a file, we can ask git to tell us the status of
of our directory.
git status
And if we want git to tell exactly what's different, in the file, it can do
that too.
git diff
Let's tell git to create a record of our change
git commit README.txt
Vim (or your default editor) will open. Type a description of your changes,
called a commit message, and save the file (in Vim, you can type :wq in
normal mode).
git keeps a record of each of your changes in a log. TO see this, let's run
git log
As you're making changes, you very often will want to undo one of your previous
commits. git allows for this with its revert command.
Let's modify our directory and commit that change.
rm README.txt
git commit -a
Later, we realize that we regret this change. We can undo this. The way that
reverting works in git is by taking the state of the repository at a point in
time and bringing it back to the present.
So what we need to do is check our log, and find the hash of the commit we want to revert
git log
git revert "hash"
This will create a commit with the default message, 'Revert "Old Commit"'. Push this change back to GitHub with
git push
For an extension of this presentation and further examples and exercises in using Git, checkout out the Git 201 repository.