Using interactive rebase to ensure a clean git history

The problem

Sometimes, when working on a feature branch, your commit history can get messy. If your log looks like this:

926bdc9 - 8 minutes ago : OK, now it's fixed
b8ae898 - 10 minutes ago : Now it's really fixed
564f4db - 15 minutes ago : Fixed a small mistake
0fac50d - 20 minutes ago : Added a new feature

you should consider revising your commit history before pushing to a remote repo. To do this, you can do an interactive rebase.

Rebasing

Rebasing is a git tool for rewriting your commit history. Using rebase, you can squash multiple commits together into one, resulting in a cleaner commit history that looks like this:

926bdc9 - 8 minutes ago : Added a new feature

To do this, run:

git rebase -i HEAD~4

The -i flag runs the rebase interactively, and HEAD~4 means that the rebase will allow you to edit the last 4 commits. This command will open up an interactive rebase vim window with the following:

pick 926bdc9 OK, now it's fixed
pick b8ae898 Now it's really fixed
pick 564f4db Fixed a small mistake
pick 0fac50d Added a new feature

# Rebase ad5b2e0..6695e26 onto 559b098 (5 commands)
#
# Commands:
# p, pick <commit> = use commit
# r, reword <commit> = use commit, but edit the commit message
# e, edit <commit> = use commit, but stop for amending
# s, squash <commit> = use commit, but meld into previous commit
# f, fixup <commit> = like "squash", but discard this commit's log message
# x, exec <command> = run command (the rest of the line) using shell
# b, break = stop here (continue rebase later with 'git rebase --continue')
# d, drop <commit> = remove commit
# l, label <label> = label current HEAD with a name
# t, reset <label> = reset HEAD to a label
# m, merge [-C <commit> | -c <commit>] <label> [# <oneline>]
# .       create a merge commit using the original merge commit's
# .       message (or the oneline, if no original merge commit was
# .       specified). Use -c <commit> to reword the commit message.
#
# These lines can be re-ordered; they are executed from top to bottom.
#
# If you remove a line here THAT COMMIT WILL BE LOST.
#
# However, if you remove everything, the rebase will be aborted.
#
# Note that empty commits are commented out

To squash all four of these commits into one, pick the top commit, and squash the lower three:

pick 926bdc9 OK, now it's fixed
squash b8ae898 Now it's really fixed
squash 564f4db Fixed a small mistake
squash 0fac50d Added a new feature

Then exit the rebase window with :wq. This will open a new vim window where you can view and edit the commit messages of the commits you are rebasing:

# This is a combination of 5 commits.
# This is the 1st commit message:

Added a new feature

# This is the commit message #2:

Fixed a small mistake

# This is the commit message #3:

Now it's really fixed

# This is the commit message #4:

OK, now it's fixed

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
# Date:      Sun Nov 24 22:05:15 2019 -0600
#
# interactive rebase in progress; onto ad5b2e0
# Last commands done (5 commands done):
#    squash 559b098 4
#    squash 6695e26 5
# No commands remaining.
# You are currently rebasing branch 'feature/DAT-2701_cool_new_feature' on 'ad5b2e0'.
#
# Changes to be committed:
#   new file:   a.txt
#   new file:   b.txt
#   new file:   c.txt
#   new file:   d.txt

You can delete everything above the #Please enter line and rewrite a new commit message, and then :wq the file.

Now your commit history is clean and you can push to the remote with a neatly organized commit log.