Git Rebase Simplified: A Step-by-Step Guide for Beginners

What is Git Rebase?

Rebase is one of two Git utilities designed to integrate changes from one branch into another. Rebasing combines or moves a sequence of commits on top of a new base commit. Git rebase is the linear process of merging.

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What Does Git Rebase Do?

A Git rebase changes the base of the developer’s branch from one commit to another, so it looks like they have created their branch from a different commit. Internally, Git creates a new commit and applies it to the specified base. However, it's essential for everyone involved to understand that although the branch appears the same, it's made up of entirely new commits. When you perform a Git rebase, you are, in effect, rewriting history.

Here’s how Git rebasing compares to Git merging. Let's say you're a developer working on a new feature on a dedicated branch. Then, another development team member updates the main branch with some new commits. The situation looks like this:

Eventually, however, the team concludes that the main's new commits are relevant to the feature you are working on. So then, if you want to incorporate the new commits onto your branch, you can merge or rebase. If you decide to use Git merging, you tack on the latest commits to your new branch like this:

However, if you use Git rebase, you move your whole feature branch, starting it on the tip of the main branch so that all the new commits are now part of the whole. This action rewrites the project history by making new commits for each of the original branch's commits. So, this is how the new branch looks:

Types of Git Rebase

It can be of the following two types:

Basic Rebase

This type involves moving or combining commits from one branch into another base commit. When you reapply each of your branch commits onto another base commit, you get to flush out the merge conflicts before performing the actual merge. It is typically used to update a feature branch with changes from the main branch.

Interactive Rebase

An interactive rebase tidies your commit history before pushing or merging to the origin. It allows editing a specific file known as ‘git-rebase-todo,’ which contains the list of commits you are working with.

Also Read: All The Git Commands You Need to Know About

Benefits of Git Rebase

The key perks of Git rebase are as follows: 

• Rebase can streamline a complex commit history
• It cleans intermediate commits by transforming them into a single commit, making it easier for DevOps teams 
• It prevents the merge commit clutter found in busy branches and repositories.
• It creates a linear, streamlined log that is easier to navigate
• Rebase offers a more organized commit structure, facilitating project movement

Git Rebase Standard vs. Git Rebase Interactive

There are two different Git rebase modes: standard and interactive. A standard mode automatically grabs the commits in your current working branch and immediately applies them to the head of the passed branch.

On the other hand, Interactive mode lets you change different commits in the process instead of just scooping up everything and tossing it into the passed branch. If you use interactive mode, you can remove, split, or alter existing commits and clean up the history, and we've already touched on why clean histories are essential.

So, how do you perform a rebase?

How to Use Git Rebase?

Here’s the syntax for launching a standard Git rebase:

git rebase <base>

And here’s the syntax for launching an interactive Git rebase:

git rebase --interactive <base>

This command opens an editor that lets you enter commands for each commit you want to rebase.

Later, we’ll explore a broader range of rebase commands. But before we do, we must discuss configuration.

Git Rebase Commands

Here’s a summary of the different commands associated with Git rebase.

Git Pull Rebase

Git pull is a command that collects changes from a remote repository and integrates them with the local branch. It performs as a merge operator, but you can utilize the Git pull rebase command to rebase instead of merge.

Git Rebase Branch

Sometimes, a developer will have many commits in different branches and want to combine them into one branch. There are two options: merge or rebase, and the latter is the best choice.

First, you need to switch to the branch in question:

git checkout <branch name>

Then, just rebase to the master.

git rebase master

Git Rebase Abort

The git rebase command offers several options that help in git rebase abort.

The Quit Option

This option cleans the rebase and does not alter anything else.

If you want to abort a rebase without resetting the HEAD to the original branch, type the following:

• git rebase --quit

The quit option is an effective way to fix any rebase that wasn’t aborted correctly.

The Abort Option

The abort option completely undoes the rebase operation. When used, the HEAD is reset to the original branch.

You can cancel the rebase and reset the HEAD to its original branch using:

• git rebase --abort

The Skip Option

The skip option skips the problematic commit, which introduces the merge conflict. After a successful rebase, the commit doesn’t stay in the git history.

To restart the operation of rebase and skip a commit, use:

• git rebase --skip

Git Advanced Rebase Application

The  - - onto­ command activates a more powerful rebase type that lets you pass specific refs to become the tips of a rebase. For example, you can achieve this through this command:

 git rebase --onto <newbase> <oldbase>

Recovering From Upstream Rebase

Speaking of overwriting, how can you recover from a force push onto a branch you’re committing to? Just use git reflog and find a ref before it was rebased, then rebase the branch against the remote ref by doing the - - onto option.

Git Rebase Master

You can perform a Git master-to-branch rebase to integrate branch changes and updates into the master. Here’s the syntax for performing a master-to-branch rebase onto a develop branch.

git rebase develop master

This tactic is helpful if both the master and develop branches commit after the branch splits off. The Git master-to-branch rebase will ensure that the master and develop branches have all the commits, regardless of where they originated.

Be careful, though. After the rebase is completed, Git creates new commits with new IDs and then permanently deletes the old commits. If other users work on branches from the deleted commits, they can’t return their changes to their origin. They must work to push those developments back into the central depository.

Best Practices for Git Rebase

Git Rebase is an extremely useful command, which might lead to complicated situations if utilized incorrectly. Here are some points to consider:

• As a thumb rule, you must only use git rebase in the local repositories to avoid affecting others' work.
• Git rebase is particularly beneficial when working on a dedicated branch for a specific feature. In this context, git rebates may be used to maintain a linear and clean commit history, making it easier for software developers to track progress while pushing your commits to a remote repository.
• You might also encounter merge conflicts in your rebase workflow, especially when you have not leveraged the commits by your colleagues in the major branch for a while. To minimize conflicts, regularly rebase your branch against the main branch. This way, you can ensure you are working on the latest changes. 
• At last, prevention is better than cure. Hence, before you consider git rebase, check it with the entire team so they can offer you guidelines on where and how to use it.

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How Do You Do Git Pull Rebase in the Command Line?

Git pull rebase is an essential tool for combining changes from a remote repository into your local branch. You have to follow the given steps while performing a Git pull rebase in the command line;

• You must ensure you are on the branch where you want to update.
• You can use the Git fetch command to update your local repository with the new changes from the remote repository.
• You can use the Git pull rebase command to execute the changes from the remote branch on your local branch.
• You have to solve any complexity that occurs during the rebase process.
• You may use the Git push command to push your changes to the remote repository.

Options

It has various options that make you capable of customizing the command's behavior. Here are some of the most common options:

--onto: This option can help to specify the new base branch for the rebase operation. This option can be beneficial in moving a whole set of commits from one branch to another.

-i or—-interactive: This option lets you edit the commit history interactively during the rebase process. It is beneficial if you want to split commits, squash multiple commits into one, or edit commit messages.

-preserve-merges: This option preserves merge commits during the rebase process, helping to maintain an accurate commit history.

Incompatible Options

Some Git rebase options are incompatible with others. For example, the -i (interactive) option cannot be used with the --onto option. Before using any options with Git rebase, understand their behavior and any potential conflicts they may have with other options.

Behavioral Differences

Git merge and rebase have behavioral differences that can affect your workflow. When you use Git merge, it creates a new commit that merges the changes from two branches, and the new commit has two parent commits, one from each branch. On the other hand, Git executes the changes from one branch into another and explores whether the changes were made directly on that branch.

Splitting Commits

Splitting commits is one of the most essential and powerful features of Git, which can split commits. This feature makes you break up a large commit into smaller, more focused ones. You can use the -i or --interactive option to split a commit during a Git rebase. It will launch an interactive rebase session in which you can change the commit history. You can pause the rebase process and edit the commit using the edit option. After making the changes, you must use the Git add command to merge the changes and the Git commit --amend command to develop a new commit.

Drawback of Git Rebase

While Git rebase presents numerous benefits, there are certain drawbacks, too: 

• It doesn’t work with pull requests, as you cannot see minor changes made by someone else.
• Users cannot track when and how commits are merged in the target branch.
• To continue the rebase, you must resolve the conflicts in the order in which they were created. Unfortunately, this means additional work, as you might have to fix the same conflicts on repeat.
• It produces the feature down to fewer commits, making it challenging to acknowledge the context.

Conclusion

Mastering rebase is essential for any developer to maintain a clean and efficient project history. With this step-by-step guide, you can confidently use Git Rebase to streamline workflows, reduce merge conflicts, and organize your commits. To further enhance your version control skills and become proficient in modern DevOps practices, consider enrolling in Simplilearn’s DevOps Engineer Masters Program. This comprehensive course will equip you with the tools and techniques to excel in DevOps and software development.

FAQs

1. What is an interactive rebase?

Interactive rebase is a tool present in Git that allows users to clean their commit history by removing, changing or reordering commits. Hence, it offers an opportunity to edit individual commits in the process.

2. When should I use git rebase?

You should use it to:

• Clean history: You can create a linear, clean history by merging several commits or discarding unnecessary commits.
• Polish a feature branch: Before merging a feature branch into the major code base, you can use rebase to ensure everything stays in order.
• Edit commit messages: You can change or edit the message of a previous commit using git.
• Clean application on a remote branch: If contributing to any project that you are not maintaining, you get to rebase your work onto the remote branch, preventing the maintainer from performing any integration work.

3. Is Git Rebase dangerous?

Git is not dangerous. However, the real danger occurs while executing history, rewriting interactive rebases and pushing the results towards a remote branch, which different users share.

4. Can I rebase a public branch?

As a golden rule in Git, you must never use it on a public branch. However, a rebase updates your branch with the contents of the other branches.

5. What is the 'squash' option in Git?

The ‘squash’ option in Git in interactive rebase combines several commits into one. It helps in simplifying the commit history.