The letter A styled as Alchemists logo. lchemists Syndication Icon

Putin's War on Ukraine - Watch President Zelenskyy's speech and help Ukraine fight against the senseless cruelty of a dictator!

Published June 28, 2020 Updated June 28, 2020

Git Commit Amend

Demonstrates how to quickly modify the last commit you made.


# Hello and welcome to the Alchemists Screencasts!
# Today, we'll learn about Git Commit Amend.

# Here's our project structure and Git log:


# 💡 See *Git Log Pretty* screencast for `gl` alias details.
# As you can see, this is a simple Ruby project with a single script:

ruby calc.rb 1 2

# Hey, wait, our math is all wrong!?! 😅
# Let's fix the code:

vi calc.rb

ruby calc.rb 1 2

# Much better!
# Since our last commit introduced the bug, we can amend to fix it:

git add calc.rb
git commit --amend


# The ability to amend a commit *only* works on the *last* commit.
# Amending a commit is the fastest way to apply corrections to the previous commit.
# The bug is not only fixed but the implementation appears correct from the start. 🎉

# You might have noticed, when amending, we have the ability to edit the commit message.
# What about situations in which you only need to amend the implementation?
# Well, we can speed that up too.
# How about we print mathematical calculations instead of sentences:

vi calc.rb

# Now we can amend without editing the commit message:

git add calc.rb
git commit --amend --no-edit
ruby calc.rb 1 2

# That was definitely faster.
# Notice that we've been using `git add`, though.
# We can skip that step too.
# This time we'll modify the script to do multiplication:

vi calc.rb

ruby calc.rb 2 3

# Now we can amend these changes via a single command:

git commit --amend --all --no-edit
git status --short --branch

# Much faster!
# Note that `--all` will pick up staged changes too so be careful you don't grab too much.
# For this situation, `--all` is perfect.

# We need to make one last correction due to the commit message being outdated:

git commit --amend

git show

# We could have corrected the body earlier but wanted to demonstrate `--all`.
# At least now you can see the many uses of amending commits.

# Enjoy!
# ☿ 🜔 🜍 🜂 🜃 🜁 🜄