Lecture 3 Exercises — Git Fundamentals (1-week workload)

Objective: gain fluency with Git workflows used in collaborative HPC projects. Produce a short lab log (codes/lab03/lab-notebook.md) containing command transcripts (script logs or git status snapshots), screenshots when useful, and short reflections on pitfalls. Use a single repository under codes/lab03/ unless noted; keep commits clean and chronologically meaningful.

Exercise 1 — Repository bootstrap & hygiene¶

1. Initialize a repository in codes/lab03/ and add a starter README.md describing the experiment plus a src/ directory with a minimal program or script (any language).

2. Create .gitignore entries for build artifacts, editor configs, and datasets you expect to generate. Document why each pattern belongs there.

3. Configure local Git settings (user.name, user.email, core.editor, init.defaultBranch) and capture the output of git config --list --local.

4. Make at least two initial commits: one for the scaffold, one for the ignore/configuration setup. Include commit messages that match the lecture guidance (50-char subject, descriptive body). Paste git log --oneline into the notebook.

Exercise 2 — Intentional branching & merging¶

1. Create feature/parser and feature/report branches from main. On each branch implement a focused change (e.g., parser adds CLI flags, report adds Markdown summary). Ensure each branch contains 2+ commits.

2. Before merging, run git fetch --all and inspect divergence with git log --graph --oneline --decorate --all. Embed a screenshot or copy of the graph.

3. Merge feature/parser into main with a fast-forward. Then intentionally diverge main and feature/report so the merge requires a merge commit (e.g., edit the same paragraph in different ways). Resolve the conflict, documenting the decision process and the final merged diff.

4. Tag the resulting state as v0.1-gitlabs and push the tag to a remote (use git remote add origin <path> to another folder if GitHub is unavailable). Verify with git tag -n and git push --tags output.

Exercise 3 — History inspection & rollback practice¶

1. Use git blame, git show, and git diff main..feature/parser to answer specific questions: who added the CLI flag, which commit changed the README introduction, and what files differ between branches. Copy the commands + condensed outputs.

2. Demonstrate three undo strategies on throwaway commits: git restore <file> (working tree only), git reset --soft HEAD~1 (rewrite staging), and git revert <hash> (create corrective commit). Explain when each is safe on shared branches.

3. Simulate a mishap: create a commit with an undesirable binary file, then remove it properly using git rm --cached + .gitignore. Show that history no longer includes the blob by running git cat-file -s <hash> before/after.

4. Bundle the repository (git bundle create lab03.bundle main feature/report) or export a patch series (git format-patch main~3..main) and note how teammates could review or apply it offline.

Submission checklist¶

• Lab notebook with commands, commentary, and screenshots.

• Repository archive (lab03.bundle or .zip) plus tag v0.1-gitlabs.

• Mention open questions (e.g., how to split commits better, CLI flags you’d like to automate) for discussion in Lecture 4.