Amend and Practice

Sometimes you commit and immediately realize the message has a typo, or you forgot to include a file. git commit --amend lets you fix the most recent commit before anyone else has seen it.

Fix the Last Commit

Fix just the message

git commit --amend -m "Correct commit message here"

Add a forgotten file to the last commit

git add forgotten-file.txt
git commit --amend --no-edit

--no-edit keeps the existing commit message unchanged.

Only amend unpushed commits

git commit --amend rewrites the commit — it creates a new commit with a different hash. If you have already pushed the commit to a shared branch, amending it will cause problems for anyone who pulled the original. Only amend commits that exist only on your local machine.

If you need to fix a pushed commit, use git revert instead (covered in Undo Mistakes).

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See What You Changed

A few more inspection commands worth knowing:

Show a specific commit

git show HEAD

Displays the full diff and metadata of the most recent commit. Replace HEAD with any commit hash to inspect an older one.

See who changed each line

git blame README.md

Shows each line of a file annotated with the commit hash and author that last changed it. Useful for tracking down when and why a change was made.

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Practice: Three-Commit Loop

Make three small, independent changes to your repo. For each one, run the full loop:

edit → git status → git diff → git add → git diff --staged → git commit -m "..." → git push

Suggestions:

1. Add a ## Usage section to README.md with a placeholder line.
2. Create a new file notes.txt with today's date.
3. Add a second line to notes.txt.

After this exercise, your git log --oneline should show at least five commits. Verify all of them appear on your GitHub repo page.

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Common Mistakes at This Stage

Committing too much at once Keep each commit to one logical change. Commits that change ten unrelated things are hard to review and impossible to revert cleanly.

Vague commit messages "Update file" or "fix" tell the future reader nothing. Write messages you would want to read six months from now.

Forgetting to push Git commits are local until you push. Make a habit of pushing at the end of every working session.

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Summary

Command	What it does
git commit --amend -m "..."	Rewrite the last commit's message
git commit --amend --no-edit	Add staged files to the last commit
git show HEAD	Inspect the most recent commit
git blame <file>	See who last changed each line