If you are also one of the millions of git user, you may have also encountered the “detached HEAD state”. It might be annoying for you but it can be fixed easily.
In the Git, HEAD refers to currently checked-out latest commit of branch. However, in a detached HEAD state, the HEAD doesn’t point to any branch, butto the specific commit or the remote repository. In this article, we will explore about git head and know what the Git detached HEAD state is and some sceneriaos that cause it. Then, we will demonstrate how to save changes in a detached head so it can quickly recover from the situation.
About Git
Git is the fast, scalable, flexible and has more commands compare to the older version control systems (VCS). However learning Git might be more difficult than it was with older systems. Complex commands less intuitive user interface can lead to unwanted states which includes detached HEAD state. Now let’s talk about detached HEAD state.
What Is a HEAD in Git?
Now the question is what does HEAD actually mean in Git? To understand that, we have to take one step back and talk about fundamentals.
A Git repository is the collection of references and objects. Objects carry relationships with each other, and references point to objects tl other references. The main objects in the Git repository are commits, but some other objects also include blobs and trees. The most important references in the Git are branches, which can be think of as labels you put on a commit.
HEAD is another important types of reference. The main purpose of the HEAD is to keep track of the current point in the Git repository. In other words, HEAD is the answer to the question, “Where am I right now?”
For example, while using the log command, how does Git understand which commit it should begin displaying results from? HEAD provides the answer to this question. When you create new commit, the parent is indicated by where HEAD currently points to.
About ‘detached HEAD’ state
You have just learn that HEAD in Git is only the name of the reference which indicates the current point in the repository. So, what does it mean for it to be attached or detached?
Most of the time, HEAD points to the branch name. When you create a new commit, your branch reference is automatically updated to point to it, but HEAD remains as it is. When you change branches, HEAD is automatically updated to point to the branch you have switched to. All of this means that, in these situation, HEAD is “the last commit in the current branch.” This is the normal state, in which HEAD is attached to a branch.
If you want to keep the changes you made in the detached HEAD state, you can easily solve this issue with three simple steps:
- Creating a new branch
- Committing the changes
- Merging the changes
Benefits of using git detached HEAD
There are several benefi for using this state. A few are highlighted below:
1. You can explore any commit:
Being in a git detached HEAD state permits you to explore any commit in the commit history.
2. You can run code change experiments:
You can test out any desired code changes on the specific commit without worrying about its affect on any branch.
3. You can also debug issues
You can also debug issues in this state using the gitbisect command to find out the commit that introduced a bug.
How to fix a git detached HEAD
Most of the times, you unintentionally get into this state and want to get out of this state. And most times, you get into this state intentionally and experimentally. These are 2 possible situation you may find yourself in. Now, let’s assume you are currently in the git detached HEAD state and explore each scenario:
1. Fix a git detached HEAD if you got there unintentionally
If you got this error state accidentally and would want to get out as soon as possible, probably disregarding any accidental code changes made too.
To do this, just switch or checkout any of your existing branches on your local git repository. You can do so by running the git command:
git checkout feature_branch or git switch feature_branchWhen you run any of the commands above, the HEAD will now point to the branch reference, feature_branch.
2. Fix a git detached HEAD if you got there intentionally
You could also want to use a git detached HEAD state to check out some code changes that you may commit.
To get out of this state but still want keep these code changes, you can just create new branch and switch to it and then add and commit the changes.
# creates a new branch and then switches to it
git switch -c feature_test_branch or git checkout -b feature_test_branch
# stages your code changes
git add .
# saves your code changes in your local git repository
git commit -m “Add a commit message here” Moreover, you can run thegit branch feature_test_branch to create the feature_test_branch, followed by git checkout feature_test_branch or git switch feature_test_branch to switch or check out to feature_test_branch, following the git commands to stage and save the code changes.
How to save changes in a detached HEAD?
To keep the changes made in the detached HEAD state, use these three steps:
1. Create a new branch:
git checkout -b new_branch_name
2. Commit the changes:
git add . git commit -m "Commit message describing the changes"
3. Merge the changes:
git checkout main # or the branch you want to merge into git merge new_branch_name
Replace `new_branch_name` with the desired name for your new branch, and `Commit message describing the changes` with an appropriate commit message.
Best Practices to Avoid Git detached HEAD?
If you also want to avoid the git detached HEAD state, then here are some of the best practice discussed:
1. Check out a branch reference:
Always check out the branch reference and qvoid switching directly to the tag, commit, or remote branch.
2. Use git rebase cautiously:
Use git rebase cautiously. If the merge conflict occurs during the rebase operation then Git can pause the rebase operation and put in the detached state.
Conclusion
In conclusion, the git detached HEAD state usually occurs when you are not on the branch but directly on the specific commit. There are also different ways to get to this, but the common situation is to check out to the commit by its hash. You can easily get out of the git detached HEAD state by running the git switch or git checkout command.
A git detached HEAD also provide some benefits. For instance, you can use it to test out experimental code logic or commit that you think might have contain some bugs into the codebase of the project. Now that you understand what the git detached HEAD is, you won’t be get confused while encountering it again in the future. The git detached HEAD state can be very useful for you if you understand it really well, what it is and how it works.
