Master Git Rebase: A Beginner’s Step-by-Step Guide to Understanding and Using Git Rebase
Git rebase is a fundamental command in Git used to integrate changes from one branch into another by moving or combining commits. Unlike merging, which creates a new commit to combine histories, rebasing rewrites the commit history to produce a linear sequence of commits. Essentially, it allows developers to change the base of their branch from one commit to another, making it appear as if the branch was created from a different starting point.
Rebasing is often described as a “linear” way of combining commits because it avoids the complex merge commits that sometimes clutter the project history. Instead, it creates a cleaner, more streamlined sequence of commits.
When working on a project, multiple developers often create branches to develop new features or fix bugs. These branches diverge from the main branch at different points in time. Over time, the main branch evolves as new commits are added by various team members.
If you continue to work on your feature branch without updating it with the latest changes from the main branch, you might run into conflicts later. Git rebase helps by allowing you to “rebase” your branch onto the latest commit of the main branch, ensuring your work includes all recent updates. This process keeps your branch up-to-date and avoids complex merges.
When performing a rebase, Git essentially performs the following steps internally:
This rewriting of commit history means that although your branch looks the same after the rebase, it is composed of new commits with new commit IDs.
Both rebase and merge are used to integrate changes from one branch into another. The difference lies in how they handle history.
When you merge, Git creates a new commit that combines the histories of both branches. This results in a branching history with merge commits, which can sometimes become complex and harder to follow.
With rebase, you relocate your commits onto the latest commit of another branch, resulting in a straight, linear history. This makes the project history cleaner and easier to navigate.
However, because rebase rewrites history, it requires caution when collaborating, especially when working with shared branches.
Imagine you are developing a feature on a branch called “feature-branch,” which was created from the main branch. Meanwhile, the main branch has received new commits from other team members. To incorporate those changes into your feature branch, you have two options:
If you choose to merge, your history will include the merge commit. If you choose to rebase, your branch will look like it was started from the latest commit on the main branch, resulting in a clean, linear history.
The basic rebase involves moving commits from your current branch and applying them on top of another branch’s latest commit. This helps incorporate upstream changes from the main branch into your feature branch before the final merge. By resolving conflicts during rebasing, you ensure your commits will apply cleanly when merged later.
Basic rebasing is commonly used to update feature branches with the latest changes from the main branch, reducing merge conflicts and keeping the history linear.
Interactive rebase is a powerful feature that allows developers to edit, reorder, combine, or remove commits before pushing them to a remote repository. When running an interactive rebase, Git opens an editor displaying a list of commits involved. You can then choose actions for each commit, such as:
This process helps maintain a clean and meaningful commit history, which is crucial for collaboration and code review.
Interactive rebasing is particularly useful in these scenarios:
Interactive rebase offers granular control over the commit history, making the project easier to understand and maintain.
One of the main advantages of rebasing is the creation of a clean, linear commit history. This makes it easier to understand the progression of changes without the noise of merge commits cluttering the log.
In projects with multiple contributors and frequent merges, the commit history can become complex and difficult to follow. Rebasing eliminates the unnecessary merge commits, making the history more concise.
A linear history simplifies reviewing code changes, as each commit represents a clear step in development. It also helps when debugging because it’s easier to trace the changes that led to a bug.
By using interactive rebase, developers can organize commits into meaningful groups, improving project documentation and understanding.
Rebasing helps keep branches updated with the latest changes from the main branch, reducing conflicts and improving collaboration among team members.
The standard rebase mode automatically takes the commits from your current branch and reapplies them on top of another branch’s tip. This process is straightforward and usually involves minimal manual intervention unless conflicts occur.
The basic syntax for a standard rebase is:
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git rebase <base-branch>
For example, if you want to rebase your feature branch onto the main branch, you would first check out your feature branch and then run:
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git rebase main
Git will sequentially replay your commits on top of the main branch’s latest commit, allowing you to resolve conflicts if they arise.
Interactive rebase is invoked using the– interactive (or -i) flag:
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git rebase –interactive <base-branch>
This command opens a text editor listing the commits that will be rebased, along with commands you can apply to each commit, such as pick, squash, edit, or drop.
Common uses of interactive rebase include:
By refining the commit history before pushing changes, developers ensure the repository’s history remains clean and understandable.
Interactive rebase provides more control over the commit history, enabling developers to craft a narrative that accurately represents the development process. It is especially useful before merging a feature branch to maintain a clean, professional project history.
Here is a summary of key Git rebase commands and their purposes:
Conflicts are common during a rebase, especially when your commits touch the same code areas as recent changes on the base branch. When a conflict occurs:
Once resolved, stage the changes using:
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git add <file>
Then continue the rebase with:
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Git rebase– continue.
If you decide the conflict is too complicated or the rebase should be stopped, you can abort with:
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git rebase– abort
This resets your branch to the state before the rebase started.
git pull is a command that fetches changes from a remote repository and merges them into the current branch. By default, it performs a fetch followed by a merge.
Instead of merging, you can configure Git to rebase your changes on top of the fetched branch during a pull. This avoids unnecessary merge commits and maintains a cleaner history.
To perform a pull with rebase, use:
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git pull– rebase
Alternatively, you can set this behavior as the default for all pulls on your repository with:
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git config– global pull. rebase true
Orr for a specific branch:
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git config branch.<branch-name>. rebase true
This is particularly helpful for developers working on shared branches to avoid merge commits when syncing their local branches with upstream changes.
When working on a feature branch, you often want to integrate the latest changes from the main branch to keep your work current and minimize conflicts before merging back.
The workflow is:
Switch to your feature branch:
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git checkout feature-branch
Rebase onto the main branch:
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git rebase main
This reapplies your feature branch commits onto the latest commit in the main branch.
Sometimes, a developer might want to combine commits from different branches. Rebasing is an efficient way to move the commits from one branch onto another, creating a coherent branch that integrates the work.
The steps typically involve:
For example:
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git checkout feature-branch
git rebase develop
This places your feature branch commits on top of the current state of the develop branch.
The– onto option provides advanced control during a rebase by allowing you to specify a new base commit for a subset of commits, rather than rebasing the entire branch.
The syntax is:
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git rebase –onto <newbase> <oldbase> [branch]
Suppose you want to move commits that come after commit A onto commit B. You can do:
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git rebase –onto B A feature-branch
This takes all commits on the feature-branch after commit A and reapplies them onto commit B.
This is particularly useful when you want to:
Sometimes, rebasing can go wrong, especially when rewriting history with force pushes. To recover:
For example:
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git reflog
git reset –hard <commit-hash>
You can then rebase carefully again, or merge as needed.
Because rebase rewrites commit history by creating new commit IDs, you must be cautious when pushing rebased branches to shared repositories.
After a rebase, you will typically need to force push:
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git push– force
Or more safely:
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git push– force-with-lease
The– force-with-lease option protects against overwriting others’ work by ensuring the remote branch is in the expected state before pushing.
Merge example:
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* Merge commit (combines branches)
|\
| * Feature commit 2
| * Feature commit 1
* | Main commit 3
* | Main commit 2
* | Main commit 1
Rebase example:
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* Feature commit 2 (rebased)
* Feature commit 1 (rebased)
* Main commit 3
* Main commit 2
* Main commit 1
Rebase produces a straight, linear history, while merge shows branch points and merges explicitly.
Conflicts during rebase occur when changes in your branch overlap or contradict changes in the base branch.
Typical causes include:
When Git encounters a conflict during rebase:
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git add <file>
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git rebase– continue
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git rebase– skip
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git rebase– abort
Avoid rebasing public branches shared with others, as rewriting history will require others to manually fix their local branches.
Regularly squash, edit, or reorder commits to make history more readable and meaningful.
Before rebasing and force pushing, notify team members to avoid conflicts or lost work.
This practice helps incorporate upstream changes early, reducing complex conflicts later.
Run tests or build the project after rebasing to ensure changes integrate smoothly.
By default, git pull fetches changes from the remote repository and merges them into your current branch, potentially creating a merge commit. Using git pull– rebase changes this behavior by rebasing your local commits on top of the upstream changes instead of merging.
This keeps the commit history linear and avoids unnecessary merge commits, which is especially helpful when collaborating with a team.
Run this command to fetch and rebase:
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git pull– rebase
This command will:
You can set Git to always use rebase instead of merge when pulling:
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git config– global pull. rebase true
Alternatively, for a single repository:
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git config pull.rebasee true
This configuration helps maintain a cleaner history by default.
In complex projects, you might have multiple feature branches with independent commits. Sometimes you want to combine those commits into a single branch to simplify integration or deployment.
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git checkout feature-branch
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git rebase main
This will:
If you want to combine changes from multiple branches, you can rebase one feature branch onto another:
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git checkout feature-branch-2
git rebase feature-branch-1
After rebasing, all commits from feature-branch-2 will be placed on top of feature-branch-1 commits, making a linear history.
Sometimes, during a rebase, conflicts may be complicated or the rebase may no longer be desirable. Git provides options to stop or cancel the rebase process.
To abort a rebase and return to the original branch state:
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git rebase– abort
To quit a rebase without resetting HEAD:
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git rebase– quit
Use these commands carefully, depending on your needs.
Decide when and where rebasing fits best in your workflow. Use it primarily to keep feature branches updated and histories clean before merging.
Always inform your team before rebasing shared branches or force pushing rebased commits to remote repositories.
Interactive rebasing helps polish commit history by squashing minor fixes or organizing logical changes into meaningful commits.
Never rebase commits that have been pushed to shared branches unless everyone involved agrees and understands the implications.
Before complex rebases, consider creating a backup branch:
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git branch backup-feature-branch
This protects against data loss in case you need to restore.
Practice resolving rebase conflicts to speed up your workflow and reduce errors.
Rebasing merge commits can be complex and error-prone. Instead, use merges for those situations.
Git rebase is a powerful tool for managing branch histories, creating a cleaner, linear commit structure, and integrating changes from one branch onto another. It offers significant advantages over merging when used correctly, such as simplifying project history and making it easier to understand.
Understanding the differences between standard and interactive rebase, along with advanced options like– onto, allows developers to tailor rebasing to their workflows. However, care must be taken, especially with public branches, as rebasing rewrites history and can disrupt other collaborators.
Mastering Git rebase commands like– continue,– skip,– abort, and knowing how to handle conflicts are essential skills for developers working in team environments. Using Git pull with rebase further enhances collaboration by keeping local changes aligned cleanly with remote updates.
When done thoughtfully and collaboratively, Git rebase helps streamline development workflows, improve code quality, and maintain a clear project history.
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