3. The Result:
After the git revert command completes, your repository's history will have a new commit. This new commit will effectively remove the changes that were introduced by the commit you reverted. Your working directory and staging area will reflect these undone changes.
Important Considerations:
* Shared Repositories: git revert is the recommended way to undo changes in a shared repository. It makes the undo operation explicit in the commit history, making it clear to everyone what happened and avoiding the potential problems that can arise from rewriting history with git reset.
* Multiple Commits: You can revert a range of commits. However, it's generally recommended to revert one commit at a time to avoid potential conflicts and make the history clearer.
* Conflicts: If the changes in the commit you're reverting conflict with changes made in subsequent commits, Git might prompt you to resolve these conflicts manually, just like during a merge.
* The Reverted Commit Still Exists: Importantly, git revert does not delete the original commit. It creates a new commit that undoes its effects. The original commit remains in the history.
How Does Git Revert Command Work?
let's dive deeper into how the git revert command actually works under the hood.
At its core, git revert operates by carefully calculating and applying the inverse diff of the target commit. Here's a breakdown of the process:
1. Identifying the Target Commit:
* When you provide a commit hash (e.g., git revert abcdef123), Git first identifies the specific commit you want to undo. It retrieves the snapshot of the repository's state before that commit was made and the snapshot after that commit was made.
2. Calculating the Diff:
* Git then calculates the diff (the set of changes) that were introduced by the target commit. This diff essentially describes what lines were added, deleted, or modified in the files between the "before" and "after" snapshots of that commit.
3. Generating the Inverse Diff:
This is the crucial step. git revert doesn't simply go back to the previous commit. Instead, it computes the inverse of the diff it just calculated.
* Additions become deletions: If the target commit added lines to a file, the inverse diff will specify the deletion of those same lines.
* Deletions become additions: If the target commit deleted lines, the inverse diff will specify the addition of those same lines (effectively restoring them).
* Modifications are reversed: If the target commit modified lines, the inverse diff will contain the changes needed to go back to the original content of those lines.
4. Applying the Inverse Diff:
* Git then takes the current state of your branch (typically the HEAD commit) and applies the inverse diff. This means it makes the changes in your working directory and staging area that effectively undo the changes introduced by the target commit.
5. Creating a New Commit:
Finally, Git automatically creates a new commit that records these changes (the applied inverse diff). This new commit becomes the latest commit on your current branch.
The metadata of this new commit will typically include:
* A unique SHA-1 hash.
* The author and committer information (usually the same as the user running the git revert command).
* A commit message (often pre-filled by Git indicating it's a revert of the specified commit).
* The parent commit(s) of this new revert commit will be the commit that was HEAD before you ran the git revert command. The original commit being reverted is also often referenced in the commit message.
Analogy:
Think of it like this: Imagine you have a recipe (your Git history). A commit is like a step in the recipe where you add or modify ingredients. git revert isn't like going back to a previous version of the recipe. Instead, it's like creating a new step that explicitly undoes the changes made in a specific earlier step. If a step said "add 1 cup of flour," the revert step would say "remove 1 cup of flour."
