How to Abort a Merge in Git

What is git merge?

Git is a well-known distributed version control system that allows developers to work on the same project, enabling collaboration, tracking changes, and maintaining different versions of a codebase. Git records changes to files through commits. Each commit is a snapshot of the project at a particular time. On the other hand, branches are separate lines of development within the project, allowing developers to work on separate features or bug fixes simultaneously.

As developers work on different features or fixes, they may need to use the merge functionality in Git to incorporate the changes from one branch into another. They typically need it when they have finished working on a feature or bug fix on a particular branch and want to integrate those changes into the main branch (or any other branch they are working on). To perform a merge operation in Git, you can use the git merge command.

However, performing a merge operation may sometimes lead to merge conflicts or undesirable results that require you to cancel the Git merge. In this article, we’ll discuss how to cancel a merge in Git, covering different scenarios and best practices.

Let’s start by looking at the scenarios where you should cancel a merge in Git.

When should we abort a merge in Git

There are several scenarios where you should abort a merge in Git, including:

• Merge Conflicts Are Too Complex to Resolve: Sometimes, Git cannot automatically resolve differences between the branches being merged. If you encounter conflicts during a merge, resolve them manually before proceeding or abort the merge if necessary.
• Mistakenly Merged the Wrong Branch: If you realize that you’ve merged the wrong branch or chose the wrong branch to merge into, you need to abort the process.
• Unexpected Issues: If new issues arise in the merged code (e.g., bugs or integration issues), you can ideally abort the merge and start over.
• Change in Merging Strategy: If a rebase is preferred over a merge or another approach is required, aborting the merge ensures a clean start with the new strategy.

Next, let’s discuss the different commands we can use to abort a merge in Git.

How to abort a merge in Git

Two commands can be used to abort a merge in Git:

• git merge --abort
• git reset --merge

We’ll go through both of these commands in the upcoming sections.

Before that, let’s set up a suitable environment for the demonstration of these commands.

Setting up the environment

Firstly, you need to create a local Git repository, which you’ll work on.

To do that, open the terminal on your local machine and run these commands to create and navigate to the folder demo:

mkdir demo
cd demo

Then, initialize a Git repository inside demo:

git init

This command creates the necessary configuration files that track changes in your project.

Next, run this command to check which branch you’re currently on:

git status

The output suggests that you’re currently on the main branch (This could be master or any other custom primary branch):

On branch main

No commits yet

nothing to commit (create/copy files and use "git add" to track)

After that, create a file named file.txt on the main branch and insert the text Hello, World! into it:

echo "Hello, World!" > file.txt

Then, add and commit the changes:

git add file.txt
git commit -m "Add file.txt"

Once you’re done committing the file, create and switch to another branch named test in the repository:

git switch -c test

While on the test branch, open file.txt in Nano, a useful command-line text editor:

nano file.txt

Next, replace the existing line in the file with a new one:

Hello, Codecademy!

After editing, save the modifications and exit the Nano text editor to return to the default terminal mode.

Then, add and commit the changes:

git add file.txt
git commit -m "Modify file.txt"

Switch back to the main branch again:

git switch main

On the main branch, you will modify file.txt again, just as you did on the test branch.

So, start by opening file.txt on Nano:

nano file.txt

Next, replace the existing text in the file with a new one:

Hello!

Once done, save the changes and exit Nano to return to the default terminal mode.

Then, add and commit the changes:

git add file.txt
git commit -m "Modify file.txt again"

Finally, try merging the test branch to the main branch:

git merge test

Upon running the command, the merge operation will commence. However, it will fail eventually, and a message will pop up in the terminal:

Auto-merging file.txt
CONFLICT (content): Merge conflict in file.txt
Automatic merge failed; fix conflicts and then commit the result.

This message indicates that the merge process has failed due to a merge conflict in file.txt on the main branch. A merge conflict occurs when both the branches that are being merged contain conflicting changes in the same file(s). In this case, the steps that you followed are designed to create this conflict, setting up the ideal environment for the demonstration of the merge abortion commands.

Moreover, it’s important to note that while the merge operation has failed, it hasn’t been aborted yet - meaning the process is still in progress. So, you can abort the merge here to restore the repository to the state before the operation began.

In the next section, we’ll learn how to abort a merge in Git using the git merge --abort command.

How to abort a merge in Git using git merge –abort

The git merge command allows you to cancel an in-progress merge using the --abort flag.

Here’s how you can use the git merge --abort command to abort the merge operation you initiated:

git merge --abort

The git merge --abort command gets rid of all the unresolved merge conflicts and restores the repository to the state before the merge operation was initiated.

Next, run the git status command to verify if you’ve successfully aborted the merge:

git status

If the operation is successful, the output should resemble:

On branch main
nothing to commit, working tree clean

In the next section, we’ll discover how to abort a merge in Git using the git reset --merge command.

How to abort a merge in Git using git reset –merge

Another command that you can use is the git reset command. This command allows you to undo changes made in a specific commit(s) and abort a merge in Git (using the --merge flag).

Here’s how you can use the git reset --merge command to abort the same merge operation:

git reset --merge

Just like git merge --abort, the git reset --merge command removes all the unresolved merge conflicts and resets the repository to the state before the merge operation was started.

Next, run the git status command to verify if the merge operation is aborted:

git status

If you get an output like this, then you’ve successfully aborted the merge:

On branch main
nothing to commit, working tree clean

Now that we’re done discussing how to abort a merge in Git using the git merge --abort and git reset --merge commands, let’s discover some key differences between these commands.

Key differences between git merge –abort and git reset –merge

Here are some key differences between git merge --abort and git reset --merge:

Next, let’s discuss some best practices that you can follow while aborting a merge in Git.

Best practices for aborting a merge in Git

While Git gives us the flexibility to abort a merge, it’s important to approach this action carefully. Here are some best practices to consider when aborting a merge in Git:

• Always Have a Backup: Before aborting a merge, it’s a good idea to create a backup of the current state of the project, such as by storing it in a new branch. This way, you can preserve your work and have an option to come back to it later. Before that, ensure that you stash the uncommitted changes in the repository.
• Clean Up Untracked Files If Needed: When aborting a merge, Git removes staged and committed changes, but untracked files may still exist. Use git status to review the workspace and remove unwanted untracked files.
• Try Resolving Conflicts First: If you’re aborting a merge because of conflicts, try resolving them first before performing the abort operation since this may eventually eliminate the need to abort the merge in the first place.
• Communicate With Your Team: If you’re working in a collaborative environment, let your team know that you’re aborting a merge to avoid confusion or conflicts in the repository.

Conclusion

In this article, we covered the several methods that you can use to cancel a merge in Git. We also went through some suitable merge abortion scenarios and best practices that you can follow while aborting a merge in Git.

Aborting a merge enables you to stop an ongoing merge operation and revert the repository to the pre-merge state and prevent broken code or unnecessary merge commits. It also helps maintain a clean Git history and allows you to reassess your approach before attempting another merge.

If you want to learn more about Git branching and collaboration, check out the Learn Git: Branching and Collaboration course on Codecademy.