Git Application Day

Five exercises, each starting from a broken or messy repository. Fix each one using the Git commands covered in class.

Repository: https://github.com/cmsc398w/git-application-day

Submission

After finishing each exercise, run the commands in its Submit section and paste the output into a file named answers.txt. Label each answer:

=== Exercise 1 ===
<paste output here>

=== Exercise 2 ===
<paste output here>

Upload answers.txt and the entire application-day folder (zipped) to Gradescope. The zip must include the exercise/ subdirectory for each exercise.

Exercise 1: Merge Conflict (10 min)

cd 01-merge-conflict
source setup.sh
cd exercise

Two branches both modified file.txt. Merge them so both lines end up in the file.

Run git log --oneline --graph --all to see where the branches diverged.
Merge merge-conflict-branch1 into master.
Open file.txt, remove the conflict markers, and keep both lines.
Stage file.txt and complete the merge.
Confirm with git log --oneline --graph.

Submit: git log --oneline --graph and cat file.txt

Exercise 2: Reset (10 min)

cd 02-reset
source setup.sh
cd exercise

The repo has 10 commits. Step backward using different reset modes, then use revert to undo a commit without rewriting history.

git log --oneline to see the starting state.
git reset --soft HEAD~1 — check git status and git log. Where did commit 10 go?
git reset --mixed HEAD~1 — what is different from --soft?
git reset --hard HEAD~1 — what changed compared to --mixed? Note that 9.txt and 10.txt are still present. Why?
You are now at commit 7. Run git revert HEAD~1 to undo commit 6.
Confirm with git log --oneline. You should see 8 commits, the most recent a revert.

Submit: git log --oneline and ls

Exercise 3: Detached HEAD (10 min)

cd 03-detached-head
source setup.sh
cd exercise

You checked out an old commit and HEAD is detached. Any commits made here are not attached to a branch and may be discarded.

git status — read git’s description of the state.
git log --oneline --graph --all — find where HEAD and master are.
Create hotfix.txt, add it, and commit with message hotfix: emergency patch.
Run git log --oneline --graph --all to see the floating commit.
Save it: git branch hotfix
Switch back: git checkout master
Cherry-pick the hotfix commit onto master.
Confirm with git log --oneline --graph --all.

Submit: git log --oneline --graph --all and ls

Exercise 4: Save My Commit (12 min)

cd 04-save-my-commit
source setup.sh
cd exercise

The repo was reset to an early commit. holygrail.txt is gone from the working directory, but the commit that added it still exists in git’s object store — just not reachable from any branch. git reflog records every position HEAD has been at.

git log --oneline to see the short history.
ls to confirm holygrail.txt is missing.
git reflog to find the commit with message found the holy grail.
git cherry-pick <sha> to bring that commit onto master.
ls and cat holygrail.txt to confirm the file is back.

Submit: git log --oneline, ls, and cat holygrail.txt

Exercise 5: Bad Commit (10 min)

cd 05-bad-commit
source setup.sh
cd exercise

One of five commits introduced badfile, which should never have been committed. Use git bisect to find it by binary search, then git revert to undo it without rewriting history.

A commit is bad if badfile exists. A commit is good if it does not.

git log --oneline to see the history.
git bisect start
git bisect bad to mark the current state.
Mark the first commit good: git bisect good <sha>
For each commit git checks out, run ls. Mark it good or bad accordingly.
When bisect identifies the culprit, run git bisect reset.
git revert <bad-commit-sha> — accept the default message.
ls to confirm badfile is gone.

Submit: git log --oneline and ls

Grading

Each exercise is worth 10 points (50 pts total).

Exercise	What is checked
1	`file.txt` has no conflict markers, contains both lines, merge commit exists
2	Log has exactly 8 commits, most recent is a revert, `8.txt` removed
3	HEAD is on master, `hotfix` branch exists, `hotfix.txt` is present, master has 5 commits
4	`holygrail.txt` exists and contains `42`
5	`badfile` is gone, a revert commit exists in the log