Practical Git: Rewriting Commit History
Though a large part of our day-to-day Git usage is centered around making commits and forging ahead to build a version history, it’s not uncommon to need to edit or adapt this history. Below I’ll be looking at some common scenarios and commands that can be used to have greater control over commits.
Like the previous post Practical Git Branching – Software Consulting – Intertech, the workflows below are part of a practical toolset for reoccurring situations when working in a repository. This post assumes the reader has a working familiarity with Git, including writing commits, branching, and an understanding of local vs remote repositories.
Adding a specific commit to a branch
Cherry Picking
If we’d like to add a commit from one branch to another, but not combine the entire history of both branches through a merge, we should cherry-pick the commit. This is a viable solution no matter where the commit is in the other branch’s history. Cherry picking is typically used to add a hotfix or small bug-patching commit.
Let’s imagine that in the process of implementing a feature for user forms, a developer working on their own branch has fixed an existing bug. We want the bug fix, but not their in-progress work or commits.
We’ll first fetch their branch from the remote and checkout the branch.
Then run “git log” to show commit history.
git log 
git cherry-pick 50d29c55
Undoing Commits When Working Solo
Soft Resetting
Performing a soft reset is a quick and handy way to rework a commit. This allows us to remove the commit from branch history while restaging the changes that were tracked for that commit.
Make note that if the branch was previously pushed or published, a reset will cause problems for collaborating developers who have pulled from the remote branch in between this reset. If we’re working in a collaborative team scenario, this negative side-effect can be combatted by instead using the revert command mentioned in the next section.
Let’s say we’ve just committed work which adds styling for a header, footer, and our primary site container. We soon learn that the client would like these app components styled differently and we must make changes. We can reset that most recent commit and update the implementation from our restaged changes.
git reset —soft HEAD~1
The number after the tilde represents n number of commits going backward in the branch history. For example, if we entered “HEAD~3” we’d see the last three commits removed, with modifications returned to staging status.
Undoing Commits When Working with a Team
Reverting a Commit
When we revert a commit, we’re simply adding a new commit that reverses the changes of the commit or commits we specify. This command is hugely valuable because the reversal is performed by Git, not the developer.
A specific commit anywhere in the repo’s history can be reverted by running
git revert <commit-hash>git revert HEAD~2..HEADgit revert 0756c88..323hfd3Just like the above example, we’ll revert the two commits shown below by specifying the range.
git revert cddaa15..331ddac
In Conclusion
Documentation on the above commands can be found below.
Git – git-cherry-pick Documentation
Git – git-reset Documentation
Git – git-revert Documentation
About Intertech
Intertech is a Software Development Consulting Firm that provides single and multiple turnkey software development teams, available on your schedule and configured to achieve success as defined by your requirements independently or in co-development with your team. Intertech teams combine proven full-stack, DevOps, Agile-experienced lead consultants with Delivery Management, User Experience, Software Development, and QA experts in Business Process Automation (BPA), Microservices, Client- and Server-Side Web Frameworks of multiple technologies, Custom Portal and Dashboard development, Cloud Integration and Migration (Azure and AWS), and so much more. Each Intertech employee leads with the soft skills necessary to explain complex concepts to stakeholders and team members alike and makes your business more efficient, your data more valuable, and your team better. In addition, Intertech is a trusted partner of more than 4000 satisfied customers and has a 99.70% “would recommend” rating.
