Basic Git Rebase Exercise

Here is an example of how to use git rebase to create a clean branch history. This post follows the format of an exercise you can follow to understand the concepts, or you can just read through it, you do you 👍

Visual Summary of Moving your branch's base to another

Go from this

-(0)--(1)--(2) master
    \ 
    (R1)--(R2) rebase1

To This

You'll get something like this:
-(0)--(1)--(2) master
                \ 
                (R1)--(R2) rebase1

Bonus: after a clean rebase, you can merge rebase1 to master cleanly

You'll get something like this:
-(0)--(1)--(2)--(R1)--(R2) master

Steps Summary

• Make a feature branch
• Make commits on feature branch
• Make commits on master
• Rebase feature branch (move the branch start to the tip of master)
• Move the feature branch into master (merge, with no extra commit)

Exercise

Make a feature branch

Create a new rebase1 branch off of master

git checkout master
git branch rebase1
git checkout rebase1

Make commits on feature branch

Make a few commits while on the rebase1 branch. For convenience, make commit messages something like the following so you can easily follow your own messages from each branch

rebase1 R1
rebase1 R2
etc...

Make commits on master

Make a few commits on the master branch. This will allow us to see how our history moves when we rebase. Follow a similar commit message format

master 1
master 2

Stop and observe what your commits currently look like. You can use git log while on each branch to see the recent commits. I'm a very visual person so here's a diagram of what it should be

-(0)--(1)--(2) master
    \ 
    (R1)--(R2) rebase1

Rebase feature branch (move rebase1's base to the tip of master)

Rebase rebase1 to the master branch. What you're really asking git to do is "attempt to move the start of my branch to the current HEAD of master"

git checkout rebase1
git rebase master

You'll get something like this:
-(0)--(1)--(2) master
                \ 
                (R1)--(R2) rebase1

• Using git log while on rebase1 you'll see all 5 commits in that order

Move the feature branch into master (merge, with no extra commit)

Once you've done a rebase successfully with no conflicts, you can now do a merge and it won't leave any extra commits in your history since no additional change was made

git checkout master
git merge rebase1

You'll get something like this:
-(0)--(1)--(2)--(R1)--(R2) master

• use git log to checkout your commit messages if you want to verify this really happened

Conclusion

Using rebase properly can result in a very clean looking branch history.