Splitting Your Last Commit in Git

September 05, 2020

Have you ever had a huge commit? And you want to split into multiple commits? Here is one of the way to go

Start an interactive rebase with the commit SHA1 before the commit you want to split.
```
git rebase -i sha1
```
git will open up vim or whatever default editor is with the commit you want to split. Mark this commit as ‘e’ or ‘edit’ instead of pick which would be the default. Save and exit from the editor.
Now, let us reset the last commit
```
git reset HEAD^
```
Now we can see the last commit to be un-done. And all your files from your last commit are either un-tracked / un-staged.
Add the commits you want to group using ‘git add’ and ‘git commit’
Once splitting of your commits are done. Continue re-basing
```
git rebase --continue
```
If you end up with any merge conflict, resolve them.
You have successfully split the commits.

Let us run through this with an example

Create a new folder and initialize a git repo there
```
mkdir example && cd example && git init
```

Add a file, to do the first commit

touch a.txt
git add a.txt
git commit -am "Added First commit"

Next create the larger commit you want to split

echo "Hello World" >> a.txt
touch b.txt
touch c.txt
touch d.txt
git add a.txt b.txt c.txt d.txt
git commit -m "Added Large commit"

Start an interactive rebase with first commits SHA

git log --pretty=oneline

38bfe60742d74a4ac0e3a04b768ee0f5cb094e58 (HEAD -> master) Added Large commit
ad51155ad7bf3f368c553000d1f74425a8664eb2 Added First commit

git rebase -i ad51155ad

Mark the commit as edit/e instead of pick

e 38bfe60 Added Large commit

Save & Exit
Reset HEAD by 1 commit

git reset HEAD^

Unstaged changes after reset:
M       a.txt

git status

interactive rebase in progress; onto ad51155
Last command done (1 command done):
edit 38bfe60 Added Large commit
No commands remaining.
You are currently splitting a commit while rebasing branch 'master' on 'ad51155'.
(Once your working directory is clean, run "git rebase --continue")

Changes not staged for commit:
(use "git add <file>..." to update what will be committed)
(use "git restore <file>..." to discard changes in working directory)
        modified:   a.txt

Untracked files:
(use "git add <file>..." to include in what will be committed)
        b.txt
        c.txt
        d.txt

no changes added to commit (use "git add" and/or "git commit -a")

Split your commits as you like.

git add a.txt
git commit -m "Edited a.txt"
git add b.txt
git commit -m "Added b.txt"
git add c.txt
git commit -m "Added c.txt"
git add d.txt
git commit -m "Added d.txt"

Continue the rebase

git rebase --continue

Successfully rebased and updated refs/heads/master.

Check your git log to see the cleaner commit history

git log --pretty=oneline

a8b391dcfe1b18992d26daa9a7841e1a88235bc3 (HEAD -> master) Added d.txt
134f11f3c59d7f70d3d8f5946dca7491ed3b7790 Added c.txt
d2ee4690e4482808c8453e16b767e86c9c405d40 Added b.txt
f4393b44183ad000b7ab9c5fa3e3f785f12cab83 Edited a.txt
ad51155ad7bf3f368c553000d1f74425a8664eb2 Added First commit