Rebase - biswajitsundara/gitdoc GitHub Wiki

Git Rebase allows us to change the base of our branch to be a different branch

and thereby incorporate changes from that branch into your own branch.
When we perform a Git rebase, Git first identifies the common ancestor commit of the two branches involved.
It then applies each commit of the branch being rebased one by one on top of the target branch,
effectively rewriting the history of the rebased branch.
This results in a linear, chronological sequence of commits,
which can make it easier to review and understand the development history of a project.

Caution

Git rebase should be used with caution, especially in a collaborative environment

It can alter the history of a project and potentially cause conflicts for other team members.
It is generally recommended to use Git rebase on local, feature branches before merging them into a shared branch (main or release branch)

Scenario

This is a common scenario that we cut a feature branch from master branch
We are working on the feature branch for some time
During that time our team mates have merged their code to the master branch
So our branch is behind lot of commits as of master branch
If we want to merge our code to master, we will have so many conflicts
So before merging, we can rebase our branch with master so all the latest changes come in
We resolve the conflicts if there are any and then finally merge to master

rebase

Problem

Let's replicate the scenario

1. Master branch

Has a file hello.html
The content of the file is

<html>
   <h1>Hello World</h1>
</html>

2. feature/contactus branch

Create a new file contact.html
The content of the file is

<html>
   <h1>Contact us</h1>
</html>

3. feature/about branch

Create a new file about.html
The content of the file is

<html>
   <h1>About us</h1>
</html>

Update the hello.html file

<html>
   <h1>Hello World</h1>
   <p>About us</p>
</html>

Create an PR and merge the PR

feature/contactus branch

Update the hello.html file

<html>
   <h1>Hello World</h1>
   <p>Contact us</p>
</html>

If we go to PR preview, it will say we need to resolve one conflict
The conflict is on the hello.html file

Solution

First, make sure we are on feature branch git checkout feature/contactus
Fetch the latest changes from the remote master branch git fetch origin master
Once latest changes are pulled, start the rebase git rebase origin/master
If any conflicts occur git will pause and ask to resolve the conflict
Edit the file, resolve the conflict and save the changes
Then stage the changes using git add <file>
Continue the rebase process after resolving all the conflicts git rebase --continue
Repeat steps 4-7 until all changes from the master branch have been applied to the feature branch.
Now the rebase process is complete
Push the changes to the remote feature branch git push --force-with-lease origin feature/contactus
Use --force-with-lease option to avoid overwriting any changes that have been made to the feature branch since your last push.
That's it! The feature branch should now include all the changes from the master branch.

git checkout feature/contactus
git fetch origin master
git rebase origin/master
  |
  | if conflict occurs
  | git add <file>
  | git rebase --continue
  |
git push --force-with-lease origin features/contactus

git rebase origin/master

This is a git command that replays the changes made on the origin/master branch on top of your current branch.

When you run this command, Git will first identify the common ancestor commit of your current branch and the origin/master branch.
It will then apply each commit that exists in origin/main but not in your current branch, one by one, on top of your branch.
This effectively integrates the changes made in origin/master into your branch's history.
Using git rebase helps keeping the feature branch up-to-date with changes made to the master branch
and helps to ensure a smoother merge when the feature is eventually merged back into the master branch.