git-cheatsheet

Amend a previous commit

You’ve finished your code, submitted the PR, and the CICD server spits out an issue with a 1-line change. You fix it and commit your change, just to get the next one. Then there’s another, and another, and another one. Rather than having many simple changes for 1 error at a time, you can amend your previous commit with the change so the commit history is cleaner.

git commit --amend

Go back to an old commit

This command will rewind history locally to the specified git commit.

git reset --hard <commit hash>

If you want to erase the changes that followed on the remote copy, you can additionally run:

git push -f

Which will force git to push your current history and overwrite whatever currently exists on remote.

Merge changes from branch A into branch B

This is generally not the best way to go as it replays all the changes in the git history. Instead consider a rebase.

First, make sure you have the latest remote changes locally.

git fetch
git pull

Make sure you have the branch you want to merge changes into checked out locally:

git checkout <BranchB>

And then merge the changes from branch A in:

git merge <BranchA>

Rebase changes in a branch onto a newer commit from the parent branch

This creates a clean, linear history of changes and avoids the need for merge resolutions when completing a PR.

Make sure you have the latest commits from the branch you made changes to (delta in this example) and the main branch that has been updated:

git checkout main
git fetch
git pull
git checkout delta
git fetch
git pull

The rebase the changes in delta onto the latest commits from main. Note that this needs to be done while delta is checked out:

git checkout delta
git rebase main

Move changes from a protected branch to a feature branch after accidentally committing without switching branches first

Often I will pull latest from the main branch and start making changes for the ticket I’m working on. After some progress I will then commit my changes, forgetting that I didn’t make a feature branch first. Since the main branch is protected and requires a PR to push to origin (the remote copy), I can’t do anything with those changes. In this scenario I need to move my changes from main to a feature branch. There are a couple ways I’ve found to do this.

Option 1 works conceptually by taking the following actions:

1. Undo my last commit to main
2. create & checkout a new feature branch
3. commit my changes to it

git reset --soft HEAD~1
git checkout -b feature/my-new-feature
git commit

Option 2:

1. Create a branch from my commit locally
2. Push my new branch with changes
3. Checkout my local main branch
4. Reset it to the same commit as on origin