1. Git Branch Merge

Merge Branches

We have the emergency fix ready, and so let's merge the master and emergency-fix branches.

First, we need to change to the master branch:

git checkout master
Switched to branch 'master'

Now we merge the current branch (master) with emergency-fix:

git merge emergency-fix
Updating 09f4acd..dfa79db
Fast-forward
 index.html | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Since the emergency-fix branch came directly from master, and no other changes had been made to master while we were working, Git sees this as a continuation of master. So it can "Fast-forward", just pointing both master and emergency-fix to the same commit.

As master and emergency-fix are essentially the same now, we can delete emergency-fix, as it is no longer needed:

git branch -d emergency-fix
Deleted branch emergency-fix (was dfa79db).

Merge Conflict

Now we can move over to hello-world-images and keep working. Add another image file (img_hello_git.jpg) and change index.html, so it shows it:

git checkout hello-world-images
Switched to branch 'hello-world-images'

Now, we are done with our work here and can stage and commit for this branch:

git add --all
git commit -m "added new image"
[hello-world-images 1f1584e] added new image
 2 files changed, 1 insertion(+)
 create mode 100644 img_hello_git.jpg

We see that index.html has been changed in both branches. Now we are ready to merge hello-world-images into master. But what will happen to the changes we recently made in master?

git checkout master
git merge hello-world-images
Auto-merging index.html
CONFLICT (content): Merge conflict in index.html
Automatic merge failed; fix conflicts and then commit the result.

The merge failed, as there is conflict between the versions for index.html. Let us check the status:

git status
On branch master
You have unmerged paths.
  (fix conflicts and run "git commit")
  (use "git merge --abort" to abort the merge)

Changes to be committed:
        new file:   img_hello_git.jpg
        new file:   img_hello_world.jpg

Unmerged paths:
  (use "git add ..." to mark resolution)
        both modified:   index.html

This confirms there is a conflict in index.html, but the image files are ready and staged to be committed.

So we need to fix that conflict. Open the file in our editor:

We can see the differences between the versions and edit it like we want:

Now we can stage index.html and check the status:

git add index.html
git status
On branch master
All conflicts fixed but you are still merging.
  (use "git commit" to conclude merge)

Changes to be committed:
        new file:   img_hello_git.jpg
        new file:   img_hello_world.jpg
        modified:   index.html

The conflict has been fixed, and we can use commit to conclude the merge:

git commit -m "merged with hello-world-images after fixing conflicts"
[master e0b6038] merged with hello-world-images after fixing conflicts

And delete the hello-world-images branch:

git branch -d hello-world-images
Deleted branch hello-world-images (was 1f1584e).

Now you have a better understanding of how branches and merging works. Time to start working with a remote repository!