Cherry-Picking Multiple Commits in Git: A Comprehensive Tutorial

Cherry-picking in Git is a powerful feature that allows you to select specific commits from one branch and apply them to another. This is incredibly useful when you want to incorporate specific bug fixes or features without merging the entire branch. While cherry-picking a single commit is straightforward, cherry-picking multiple commits requires a bit more finesse. This tutorial provides a comprehensive guide to various methods for cherry-picking multiple commits, their pros and cons, and important considerations.

1. The Basics: Single Commit Cherry-Picking

Before diving into multiple commits, let’s review the single-commit case:

bash
git cherry-pick <commit-hash>

Where <commit-hash> is the SHA-1 hash of the commit you want to apply. You can find the commit hash using git log or your preferred Git GUI. This command applies only that commit to your current branch. If there are conflicts, Git will pause the cherry-pick process and ask you to resolve them before continuing.

2. Cherry-Picking Multiple Commits: Sequential Method

The most straightforward way to cherry-pick multiple commits is to execute the git cherry-pick command repeatedly, in the desired order.

“`bash
git cherry-pick
git cherry-pick
git cherry-pick

… and so on

“`

• Pros: Simple and easy to understand. Clear and explicit about the order of application.
• Cons: Can be tedious and error-prone if you have many commits. Increases the chances of encountering conflicts, as each commit is applied separately. Harder to manage if you need to abort mid-process.

3. Cherry-Picking a Range of Commits

Git offers a powerful way to cherry-pick a range of commits using a concise syntax.

bash
git cherry-pick <start-commit-hash>..<end-commit-hash>

Important Note: This syntax includes all commits after <start-commit-hash> up to and including <end-commit-hash>. start-commit-hash itself is not included.

For example:

bash
git cherry-pick A..D # Cherry-picks commits B, C, and D (assuming A -> B -> C -> D)

You can also use branch names or tags in the range:

bash
git cherry-pick feature-branch~3..feature-branch # Cherry-picks the last three commits on feature-branch

The ~n notation refers to the nth ancestor of a commit. feature-branch~3 means “three commits before the tip of feature-branch“.

• Pros: Much more efficient for picking a consecutive sequence of commits. Reduces the risk of typos compared to the sequential method.
• Cons: Only works for contiguous ranges. If the commits you need are scattered, this won’t work. You still need to be mindful of the commit order.

4. Cherry-Picking a Range (Exclusive of End Commit)

If you want to cherry-pick a range of commits but exclude the ending commit, you can use the following syntax:

bash
git cherry-pick <start-commit-hash>^..<end-commit-hash>
The ^ after <start-commit-hash> indicates that the starting commit is included in the range.

Example:

bash
git cherry-pick A^..D # Cherry-picks commits A, B, and C. D is not cherry-picked.

This is equivalent to git cherry-pick A B C.

5. Cherry-Picking Multiple Non-Consecutive Commits (One Command)

While less common, you can cherry-pick multiple, non-consecutive commits in a single command:

bash
git cherry-pick <commit-hash-1> <commit-hash-2> <commit-hash-3> ...

This behaves the same as the sequential method (Section 2), but it’s all done in one go.

• Pros: Slightly less typing than the fully sequential method.
• Cons: Still prone to typos if you have long commit hashes. Doesn’t offer any real advantage over the sequential method in terms of conflict resolution or manageability. Becomes unwieldy with many commits.

6. Interactive Rebase (for Complex Scenarios)

For more complex cherry-picking scenarios, especially when you need to reorder commits, edit commit messages, or squash commits together, interactive rebase (git rebase -i) is a powerful (but more advanced) option. While not strictly just cherry-picking, it can achieve the same result and more.

bash
git rebase -i <commit-hash>

Replace <commit-hash> with the commit before the first commit you want to modify. This opens your text editor with a list of commits. You can then:

• pick: Use the commit (this is the default).
• reword: Use the commit, but change the commit message.
• edit: Use the commit, but stop for amending.
• squash: Use the commit, but meld it into the previous commit.
• fixup: Like squash, but discard this commit’s log message.
• drop: Remove the commit.

To cherry-pick using interactive rebase, you would:

1. Check out the branch you want to apply the commits to.
2. Start an interactive rebase from a point before the commits you want to pick.
3. drop all the commits except the ones you want to cherry-pick. Effectively, you’re rebuilding the history of the branch, only including the commits you chose.

4. Save and close the editor. Git will apply the changes.

5. Pros: Extremely powerful and flexible. Allows for reordering, squashing, and editing commits during the cherry-picking process.

6. Cons: More complex and requires a good understanding of Git’s rebase functionality. Can be dangerous if used incorrectly, as it rewrites history. Never use interactive rebase on commits that have already been pushed to a shared remote repository.

7. Handling Conflicts

Cherry-picking, especially with multiple commits, can often lead to conflicts if the same lines of code have been modified in both the source and destination branches. When a conflict occurs:

1. Git will pause the cherry-pick process and mark the conflicted files.
2. Open the conflicted files in your text editor. You’ll see conflict markers (<<<<<<<, =======, >>>>>>>) indicating the differing versions.
3. Edit the files to resolve the conflicts. Choose the correct version, combine the changes, or make any necessary modifications.
4. Stage the resolved files: git add <conflicted-file>.
5. Continue the cherry-pick: git cherry-pick --continue.
6. If you want to abort the cherry-pick, use git cherry-pick --abort.

8. Important Considerations and Best Practices

• Commit Order: Cherry-picking applies commits in the order you specify. Ensure the order makes sense in the context of the destination branch. Incorrect order can lead to broken code or unexpected behavior.
• Dependencies: Be mindful of dependencies between commits. If commit B depends on changes made in commit A, you must cherry-pick A before B.
• Shared History: Avoid cherry-picking commits that have already been pushed to a shared remote repository and are part of the shared history. Cherry-picking creates new commits with different hashes, which can cause confusion and problems for other developers. Consider using git merge or git rebase (carefully!) for shared branches.

• Merge Commits: Cherry-picking merge commits can be tricky. By default, git cherry-pick only applies the changes introduced by the merge itself, not the changes from the merged branch. To cherry-pick a merge commit and its associated changes, use the -m (mainline) option:

  bash
git cherry-pick -m 1 <merge-commit-hash>

  The 1 refers to the first parent of the merge commit (usually the branch you were on before the merge). You may need to experiment with -m 1 or -m 2 to get the desired result. Always carefully inspect the result of cherry-picking a merge commit.

• --no-commit Option: The --no-commit option stages the changes from the cherry-picked commit(s) without automatically creating a commit. This gives you a chance to review the changes, make further modifications, and create a single commit with a descriptive message. This is particularly useful when cherry-picking multiple commits:

  “`bash
  git cherry-pick –no-commit …

  Review and modify changes…

  git commit -m “Cherry-picked features X and Y from feature-branch”
  “`

• Documentation: When cherry-picking, it is crucial to have clear documentation. Add a comment to the commit message indicating which commits were cherry-picked and from which branch. This helps maintain a clear history and makes troubleshooting easier.

Conclusion

Cherry-picking multiple commits in Git is a valuable skill for managing your codebase. By understanding the various methods, their nuances, and the potential pitfalls, you can effectively incorporate specific changes from one branch to another while maintaining a clean and manageable Git history. Remember to choose the method that best suits your needs and always test your changes thoroughly.