02_GitRet_Example.md

A step-by-step guide on how to use each of the git reset modes (--soft, --mixed, and --hard) with examples from scratch.

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Example Setup

Let's first create a new Git repository and make some commits to demonstrate the git reset command.

Step 1: Initialize a New Git Repository

mkdir git-reset-demo
cd git-reset-demo
git init

Step 2: Create an Initial File and Commit

echo "Initial content" > file.txt
git add file.txt
git commit -m "Initial commit"

Step 3: Make Additional Commits

Let's create a few more commits.

echo "Change 1" >> file.txt
git add file.txt
git commit -m "Added change 1"

echo "Change 2" >> file.txt
git add file.txt
git commit -m "Added change 2"

echo "Change 3" >> file.txt
git add file.txt
git commit -m "Added change 3"

At this point, your commit history looks like this:

git log --oneline

Output:

<commit_hash3> Added change 3
<commit_hash2> Added change 2
<commit_hash1> Added change 1
<commit_hash0> Initial commit

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Example 1: Git Reset with --soft

Scenario:

You want to undo the last commit but keep the changes staged so you can recommit them.

Step 1: Perform a Soft Reset

git reset --soft HEAD~1

This command will reset the repository to the commit before the last one (HEAD~1).

Step 2: Check the Status and Log

git status

Output:

On branch main
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
	modified:   file.txt

git log --oneline

Output:

<commit_hash2> Added change 2
<commit_hash1> Added change 1
<commit_hash0> Initial commit

The last commit ("Added change 3") is gone from the history, but the changes are still staged and ready to be recommitted.

Step 3: Recommit the Changes

git commit -m "Recommitted change 3 after soft reset"

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Example 2: Git Reset with --mixed (Default)

Scenario:

You want to undo the last commit and keep the changes in the working directory but unstaged.

Step 1: Perform a Mixed Reset

git reset HEAD~1

This command will reset the repository to the commit before the last one (HEAD~1) and unstages the changes.

Step 2: Check the Status and Log

git status

Output:

On branch main
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
	modified:   file.txt

git log --oneline

Output:

<commit_hash2> Added change 2
<commit_hash1> Added change 1
<commit_hash0> Initial commit

The last commit ("Added change 3") is gone from the history, and the changes are now in your working directory but not staged.

Step 3: Recommit the Changes

If you want to recommit these changes, you first need to stage them again:

git add file.txt
git commit -m "Recommitted change 3 after mixed reset"

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Example 3: Git Reset with --hard

Scenario:

You want to completely undo the last commit and discard the changes in the working directory.

Step 1: Perform a Hard Reset

git reset --hard HEAD~1

This command will reset the repository to the commit before the last one (HEAD~1), and it will also discard any changes made in the last commit.

Step 2: Check the Status and Log

git status

Output:

On branch main
nothing to commit, working tree clean

git log --oneline

Output:

<commit_hash2> Added change 2
<commit_hash1> Added change 1
<commit_hash0> Initial commit

The last commit ("Added change 3") is gone from the history, and the changes are completely discarded from your working directory and staging area.

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Example 4: Git Reset by a Specific Number of Commits

Scenario:

You want to reset the last two commits, keeping changes in the working directory.

Step 1: Perform a Mixed Reset by Number of Commits

git reset HEAD~2

This command will reset the last two commits and keep the changes in the working directory.

Step 2: Check the Status and Log

git status

Output:

On branch main
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
	modified:   file.txt

git log --oneline

Output:

<commit_hash1> Added change 1
<commit_hash0> Initial commit

The last two commits ("Added change 3" and "Added change 2") are gone, but the changes are present in the working directory.

Step 3: Recommit the Changes

If needed, stage and recommit the changes:

git add file.txt
git commit -m "Recommitted changes after resetting last two commits"

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Conclusion

The git reset command is an essential tool for managing your commit history and modifying your repository's state. Use the --soft, --mixed, and --hard options depending on how you want to handle the changes in your working directory and staging area. Always be cautious, especially when using the --hard option, as it can lead to data loss if not used carefully.