Скачать или смотреть Understanding Detach Commits: How They Happen by Accident in Git

Learn what a `detach commit` is in Git, how it's unintentionally created, and the actions that can lead to these unreachable commits.
---
This video is based on the question https://stackoverflow.com/q/64064358/ asked by the user 'dogfox' ( https://stackoverflow.com/u/9895882/ ) and on the answer https://stackoverflow.com/a/64064595/ provided by the user 'Mark Adelsberger' ( https://stackoverflow.com/u/7050130/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How do I create a detach commit by accident?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding Detach Commits: How They Happen by Accident in Git

Have you ever found yourself in a situation where you accidentally created a detach commit in Git? If the answer is yes, you're not alone! Many developers experience this confusion, wondering how Git's behavior leads to such situations. This post will clarify what a detach commit is, how it occurs unintentionally, and the common operations that can cause it. Let’s dive in!

What is a Detach Commit?

A detach commit refers to a commit that is no longer reachable through any branch. This typically occurs when you perform certain actions in Git that make the commit inaccessible or unseen. Understanding why and how this happens is crucial for maintaining a clean project history and avoiding frustration while working with version control.

How Does Git Create Detach Commits Unintentionally?

There are several operations in Git that may lead to the creation of detach commits. Let’s break down each of these actions:

1. Using git commit --amend

When you use the command git commit --amend, it might seem like you're editing the last commit. However, what's actually happening is:

New Commit Creation: Git creates a new commit instead of modifying the existing one.

Change in Parent List: The new commit inherits its parent list from the previous commit but does not include the old commit as a parent.

Unreachable State: Consequently, the old commit becomes unreachable if it is not referenced by any other branch.

2. Performing a Git Rebase

Rebasing allows you to rewrite commit history, but this can lead to detach commits as well. Here’s how:

Rewriting Commits: During a rebase, Git rewrites a series of commits to create new ones based on the selected branch.

Leaving Originals Unreachable: Once the branch is moved, the original commits become unreachable since they are no longer part of the branch's history.

3. Using git reset Command

The git reset command can "un-commit" changes, leading to a similar effect:

Un-commit Actions: This action takes your branch back to a previous commit without actually deleting the accessed commits.

Restoration of Reachable Commits: The previous commits might remain in the repository but become unreachable from your branch.

4. Deleting a Branch

If you delete a branch that is pointing to a commit, that commit will also become a detach commit unless it is reachable by another branch.

5. Utilizing Git Filter-Branch

Advanced operations such as using filter-branch can unintentionally cause amendments and deletions that render certain commits unreachable.

Summary of Key Points

A detach commit happens when a commit is not reachable from any branch in Git.

Common actions that might lead to this state include:

Using git commit --amend

Performing a rebase

Utilizing git reset

Deleting branches

Executing advanced commands like filter-branch

Understanding these behaviors will not only help you avoid accidental detach commits but also improve your overall ability to navigate and utilize Git effectively. Always ensure to check the state of your commits and branches when performing operations that can change the history of your repository. Happy coding!