What plain git reset does to HEAD, the index and your files

Table of Contents

• Introduction
• What is git reset (mixed)?
• Watch it happen
• Before and after
• Where mixed sits
• Is it safe?
• How to undo it
• Try it on your repository
• Common questions
• Summary
• Next steps
• Related commands

Introduction

When you type git reset HEAD~1 with no --soft or --hard, you get --mixed, and it's the version most people actually want when they say "undo my last commit". The commit goes, your files stay, and the changes are back in your working directory as if you'd never run git add.

In this article, we'll:

1. Watch git reset HEAD~1 move main back one commit
2. See what happens to the staging area and the working directory
3. Place --mixed between --soft and --hard

What is git reset (mixed)?

git reset <commit> does two things: it moves the current branch to <commit>, and it resets the staging area to match that commit's tree. Your working directory is left as it is. The result is that changes from the undone commits, plus anything you had staged, are all sitting in your working directory as unstaged edits.

Watch it happen

Our sample repo has a clean working tree on main. Here's git reset HEAD~1:

1. Before: HEAD is attached to main at 8c02d5b, "Update dependencies", the commit that added requirements.txt.
2. main moves back one commit to "Add user settings page", and HEAD moves with it.
3. Git resets the index to match that commit, so requirements.txt is no longer tracked. It's still in the working tree as an untracked file, and feature stays put.

Before and after

The graph looks the same as after a --soft reset. The difference is in git status, which reads:

?? requirements.txt

"Update dependencies" added requirements.txt. After a mixed reset, that file is still on disk but is no longer in the staging area, and since it isn't in a0b2db3 either, Git now sees it as untracked. Compare the --soft version, where the same file shows as a staged addition.

* 1117a34 (feature) Add search tests
* e5869f0 Fix typo in search box
* fc19889 Add search box
| * 8c02d5b (HEAD -> main) Update dependencies
| * a0b2db3 Add user settings page
|/  
* 96c4fc2 Fix header layout
* ae65976 Add login page
* 3e1ffe4 Add project skeleton
* 4114b2c Initial commit

* 1117a34 (feature) Add search tests
* e5869f0 Fix typo in search box
* fc19889 Add search box
| * a0b2db3 (HEAD -> main) Add user settings page
|/  
* 96c4fc2 Fix header layout
* ae65976 Add login page
* 3e1ffe4 Add project skeleton
* 4114b2c Initial commit

Where mixed sits

Mixed is the default because it's the safe middle: it undoes commits and un-stages, both of which are reversible, and it never overwrites a file.

Is it safe?

The undone commit stays in the reflog, and every change it contained is still in your working directory. What you lose is the record of which changes were staged.

How to undo it

git reset --hard 8c02d5b

moves main back onto the original commit and restores the staging area and files to match it. Since the working directory already has those contents, nothing is overwritten.

Try it on your repository

pip install git-sim
git-sim reset HEAD~1

git-sim shows where the branch would land, which commits would leave it, and which files would drop out of the staging area.

Common questions

What does git reset do without any flags?

A mixed reset: it moves the branch to the given commit and resets the staging area to match, leaving your working directory untouched.

What is the difference between git reset --mixed and --soft?

Both move the branch. --soft keeps the staging area as it was, so undone changes stay staged. --mixed clears it, so they become unstaged edits.

Does git reset delete my changes?

Not in mixed or soft mode. Only --hard overwrites working directory files.

How do I unstage everything?

git reset with no arguments resets the staging area to HEAD without moving the branch, which unstages every file and keeps the edits.

Summary

In this article, we watched a mixed git reset move main back one commit and clear the staging area, saw the undone commit's file turn up as an untracked file on disk, and placed the default between --soft and --hard.

Next steps

git reset --soft is the same move with the staging area preserved, and git reset --hard is the one that also rewrites your files.

Related commands

• git reset --soft, keeps the changes staged
• git reset --hard, also resets your files
• git reset HEAD file, a mixed reset of one file
• git restore --staged, the modern way to unstage
• git reflog, to find the undone commit
• git commit, to recommit after re-adding