Scenario 4 - Undoing Changes | Learn Git Version Control

Step 1 - Git Checkout

When working with Git, a common scenario is to undo changes in your working directory. The command git checkout will replace everything in the working directory to the last committed version.

If you want to replace all files then use a dot (.) to indicate the current directory, otherwise a list the directories/files separated by spaces.

Task

Use git checkout to clear any changes in the working directory.

Step 2 - Git Reset

If you're in the middle of a commit and have added files to the staging area but then changed your mind then you'll need to use the git reset command. git reset will move files back from the staging area to the working directory. If you want to reset all files then use a . to indicate current directory, otherwise list the files separated by spaces.

This is very useful when trying to keep your commits small and focused as you can move files back out of the staging area if you've added too many.

Task

Move the changes from staging back to the working directory using git reset

Step 3 - Git Reset Hard

A git reset --hard will combine both git reset and git checkout in a single command. The result will be the files removed from the staging area and the working directory is taken back to the state of the last commit.

Task

Remove the changes from both the staging area and working directory using git reset

Protip

Using HEAD will clear the state back to the last commit, using git reset --hard <commit-hash> allows you to go back to any commit state. Remember, HEAD is an alias for the last commit-hash of the branch.

Step 4 - Git Revert

If you have already committed files but realised you made a mistake then the command git revert allows you to undo the commits. The command will create a new commit which has the inverse affect of the commit being reverted.

If you haven't pushed your changes then git reset HEAD~1 has the same affect and will remove the last commit.

Task

Use git revert to revert the changes in the last commit.

Note, this will open an Vim editor session to create a commit message for each commit. To save the commit message and quit vim type the command :wq for each Vim session.

Protip

The motivation behind creating new commits is that re-writing history in Git is an anti-pattern. If you have pushed your commits then you should create new commits to undo the changes as other people might have made commits in the meantime.

Step 5 - Git Revert

To revert multiple commits at once we use the character ~ to mean minus. For example, HEAD~2 is two commits from the head. This can be combined with the characters ... to say between two commits.

Task

Use the command git revert HEAD...HEAD~2 to revert the commits between HEAD and HEAD~2.

Protip

You can use the command git log --oneline for a quick overview of the commit history.

cd <directory>	Change directory
ls	List directory
echo 'contents' > <file>	Write contents to a file
cat <file>	Output contents of file

i	In Command Mode	Change into Insert Mode, you can now insert and edit text in the file
esc	In Insert Mode	Change into Command Mode, you can now execute commands
:wq	In Command Mode	Save and Exit

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Scenario 4 - Undoing Changes

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