How to git squash quickly without messing up

2018/04/29

So you have a branch with few commits and you want to squash all of them into one before sending a PR to your favorite opensource project.

Here’s how you do it.

First do,

$ git log

Scroll till you reach the upstream or origin branch commit where the current branch was branched from. Then just copy the commitid of that commit. If you branched it from the master then it will either be (upstream/master, master) or (origin/master, master) i.e

     * (HEAD of your branch)
    /
|--/ (you need the commit id of this)
|
|
(master)

Okay, now do (without “<>“)

$ git diff <COMMIT_ID> HEAD

This will show all the changes you made till now from the commit you merged, so if you git squash the these changes will be in one commit.

Now we have the <COMMIT_ID>, let’s git squash.

$ git rebase -i <COMMIT_ID>

It will open your text editor(neovim for me) and will have something similar to this:

pick 260ad1cdc a commit message (oldest commit)
pick fcbf580f0 commit message here
pick 239791001 another commit message
pick bd555ab92 yet another commit message (latest commit)

Now if you read the contents you’ll get that, to squash you can either do squash or fixup.

When you do fixup it takes care of ignoring the commit messages of the commits you want to squash.

If you use squash then you have to remove the commit messages manually. (see below)

So to squash or fixup you just replace the 2nd line and subsequent lines with squash or fixup (the last line is your latest commit and the first line is the oldest commit), but don’t worry because git is smart enough to know that you want to squash all of them to one.

So, This

pick 260ad1cdc a commit message
squash fcbf580f0
squash 239791001
squash bd555ab92

and

pick 260ad1cdc a commit message
fixup fcbf580f0 commit message here
fixup 239791001 another commit message
fixup bd555ab92 yet another commit message

are the same.

Make the edit as mentioned above and save the file. You’re done.

You can verify your changes using git log

./ Happy Hacking :)