Splitting Your Last Commit in Git

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