15  Git - Cheatsheet

Git records changes in your project; GitHub is one place to share a Git repository. This quick reference assumes that you are inside a repository and have already configured Git. For the concepts behind these commands, see the Version Control chapter.

15.1 Inspect Before You Change Anything

Task	Command	What to look for
See current branch and file state	git status	Changed, staged, and untracked files
Inspect unstaged edits	git diff	The lines you have changed
Inspect staged edits	git diff --staged	What the next commit would include
See recent history	git log --oneline -5	Recent commits and messages

Saving a file in your editor does not commit it. A commit records a snapshot of the staged changes, so inspect both the working-tree diff and the staged diff before you commit.

15.2 Make and Share a Change

git switch -c audit-campaign-data   # Create and enter a new branch
# Edit and save files in your editor
git status
git diff
git add src/prepare_data.R          # Stage only the intended file
git diff --staged
git commit -m "Check campaign join keys"
git push -u origin audit-campaign-data

Use a descriptive branch and commit message. The first push with -u sets the branch’s upstream; future pushes from that branch can usually use git push. Open a pull request on GitHub if your team reviews changes before merging.

To bring remote changes into your current branch, check where you are first:

git status
git branch --show-current
git pull

git pull updates the current branch from its configured upstream. If Git reports a conflict, inspect the affected files, decide which content to retain, and check the resulting diff before completing the merge or rebase. Do not assume that a successful pull validates your analysis.

15.3 Correct a Local Mistake

Situation	Command	Effect
Staged a file too early	git restore --staged path/to/file	Removes it from staging; keeps your edits
Want to see where a file changed	git diff -- path/to/file	Shows unstaged changes to that file
Want to discard unstaged edits to one file	git restore path/to/file	Replaces its working copy with the staged version—inspect first

Git normally tracks code and documentation; generated files and private credentials should not be added accidentally. Inspect git status and keep an appropriate .gitignore. If a credential was committed, revoke it: deleting the latest copy does not erase the earlier commit.