Git 101

In an effort to bring the team up and running on git, I’ve made this tiny guide of the most essential commands.

Initialization

To instantiate a repository for your code, you have to create a repository, stage changes and commit them.

git init .

git add Readme.org Somefile.txt

git commit -m "Initialize Repository"

So, that’s our first commit!

Sharing Code

At this point, the code only lives on my local machine, so it’s next to impossible to get involved. Let’s fix that!

git remote add origin git@github.com:hkjels/Git-101.git

Here we are saying that we would like to add a remote target with the local-reference origin to the URL git@github….

If we then do a

git push -u origin master

We send our first commit of to Github’s server. Notice that I use the -u flag. That will make this repository’s master-branch point to the origin’s master-branch for all subsequent pushes, so that you don’t have to specify anything other than git push later on.

Branching

Branch, branch, branch! If you come from the SVN-lair, you might think twice before merging because of resources and the time you’ll need to spend, but with Git it’s almost instant, so branch away!

git checkout -b "fix/typo"

We are now in the fix/typo branch, so I’ll just do that before moving on. Whistle, whistle, tada, bum, ti, dum…

git commit -a -m "Correct the typo"

Note, I discourage the use of the ~-a~ flag, but I think it’s OK for demonstration purposes

Merging

Let’s jump into our master-branch

git checkout master

From here, we can now merge in the changes made to our fix/typo branch.

git merge fix/typo

git push

The corrected code now lives in a remote repository, so others can pitch in.

The Other end

Now, imagine for a second that someone else did that last commit.

git reset HEAD~ --hard

Here we reset the tip of this branch (master) to one commit earlier than HEAD, which is the last change that was pushed.

We can simply do a

git pull

And now our master-branch is aligned with the remote origin’s master-branch.

Resolving Conflicts

Again, lets imagine that someone else did that last commit.

git reset HEAD~ --hard

Now, I will make a change to the same line as that other doofus and we will end up with a merge-conflict when I try to pull.

git commit -a -m "Make the pitch friendlier"

This will fail, for the obvious reason that we are behind the remote origin’s master.

git push

So we have to retrieve the changes. And yes, this will fail as well, because we have a conflict.

git pull

Resolving that piece of shit!..

git rebase --continue

git push