Master Git: Undo Unadded Changes, Revert Commits, and Recover Files

Why Git tracks modifications, not files

Git records each change (addition, deletion, or edit of lines) as a modification. Creating a new file is also a modification. Commits contain the set of staged modifications, not whole files.

Experiment: committing only the first modification

Append a line to readme.txt and view it with cat.

Stage the change: git add readme.txt.

Modify the file again without staging.

Commit: git commit -m "first change".

Only the first modification is included because the second change was never added to the index.

To see the uncommitted change: git diff HEAD -- readme.txt.

Committing the second modification

Run git add readme.txt again, then git commit.

Or stage the second change first and then commit, which combines both modifications into a single commit.

Discarding unadded changes

To throw away modifications that have not been staged: git checkout -- readme.txt The double‑dash -- separates the file name from a possible branch name.

Discarding staged changes

If a file is already in the index but you want to discard the change: git reset HEAD readme.txt # unstage git checkout -- readme.txt # restore the file to the last committed version

Deleting a file

File deletion is also a modification. After removing the file from the working directory, run: git rm test.txt Commit the deletion; git status will show the removed file.

Recovering a deleted file

If the file was previously committed, restore it with: git checkout -- test.txt This replaces the working‑directory version with the last committed version. Files never added to the repository cannot be recovered.

Viewing reference history

Use git reflog to list all reference updates, which helps locate previous commits for recovery.

Additional notes

When a file is both modified and staged, git reset HEAD <file> removes it from the index while keeping the changes in the working directory. Afterward you can either commit the changes or discard them with git checkout -- <file>.