OverviewTeaching: 10 min
Exercises: 10 minQuestions
What is a branch?
How can I merge changes from another branch?Objectives
Know what branches are and why you would use them
Understand how to merge branches
Understand how to resolve conflicts during a merge
What is a branch?
You might have noticed the term branch in status messages:
$ git status
On branch master nothing to commit (working directory clean)
and when we wanted to get back to our most recent version of the repository, we
git checkout master.
Not only can our repository store the changes made to files and directories, it
can store multiple sets of these, which we can use and edit and update in
parallel. Each of these sets, or parallel instances, is termed a
master is Git’s default branch.
A new branch can be created from any commit. Branches can also be merged together.
Why are branches useful?
Suppose we’ve developed some software and now we want to
try out some new ideas but we’re not sure yet whether we’ll keep them. We
can then create a branch ‘feature1’ and keep our
master branch clean. When
we’re done developing the feature and we are sure that we want to include it
in our program, we can merge the feature branch with the
This keeps all the work-in-progress separate from the
master branch, which
contains tested, working code.
When we merge our feature branch with master git creates a new commit which contains merged files from master and feature1. After the merge we can continue developing. The merged branch is not deleted. We can continue developing (and making commits) in feature1 as well.
Branching in practice
One of our colleagues wants to contribute to the paper but is not quite sure if it will actually make a publication. So it will be safer to create a branch and carry on working on this “experimental” version of the paper in a branch rather than in the master.
$ git checkout -b paperWJohn
Switched to a new branch 'paperWJohn'
We’re going to change the title of the paper and update the author list (adding John Smith). However, before we get started it’s a good practice to check that we’re working on the right branch.
$ git branch # Double check which branch we are working on
master * paperWJohn
The * indicates which branch we’re currently in. Now let’s make the changes to the paper.
$ vim journal.md # Change title and add co-author $ git add journal.md $ git commit # "Modify title and add John as co-author"
If we now want to work in our
master branch. We can switch back by using:
$ git checkout master
Switched to branch 'master'
git branchcreates a new branch
Use feature branches for new ideas and fixes, before merging into
merging does not delete any branches