git-sh-workshop

Installation

Should work on OS X and Linux, untested on Windows.

git-sh

For the prompt and to avoid writing git in front of every command.

1. Clone https://github.com/krlmlr/git-sh
2. Run make in this directory
3. One of:
   • Run mkdir -p ~/bin; ln -s ${PWD}/git-sh ~/bin/git-sh in this directory
   • Run sudo make install in this directory

Git aliases

For the shortcuts covered here: s, d, a, co, ...

Paste the contents of config.sh into your terminal, or run:

curl https://raw.githubusercontent.com/krlmlr/git-sh-workshop/master/config.sh | sh

rstudio.cloud instance

• https://rstudio.cloud/project/143049
• Make sure to click "Save as copy" (red icon top right)

Exercises

Restart all exercises with:

git checkout .
git clean -fd
git reset --hard origin/master

A: Basic commands

1. Run script.R. What does it show?

   • Ctrl + Shift + Enter or Cmd + Shift + Enter

2. Switch to the terminal, start git sh

   • Alt + Shift + R, git sh

3. Make sure that you have a clean working copy.

   • s

4. Add a show_blue() function, and a call to that function in script.R. Inspect the changes.

   • d

5. Commit both changes as an atomic unit.

   • aa, s, dc cim

6. Add a comment to your code. Commit without changing the commit message.

   • ciao

7. Take a look at the log.

   • l, lp

8. Start implementing a show_pink() function, then throw it away.

   • coa

9. Create a new file, save it, then throw it away.

   • clean -n, clean -f

10. Create a new file in a new directory, then throw it away.

    • clean -nd, clean -fd

11. Create a new file. What does the status look like?

    • a

12. Remove this file. What does the status look like?

    • rm

13. Reset to the previous commit. Check the status.

    • qhp

14. Reset to the previous commit once more. Check the status.

    • qhp

B: Interactive commands

1. Add a show_yellow() function at the top, and a show_cyan() function to the bottom of functions.R, and calls to script.R. Commit these changes as atomic units, edit the commit message (and perhaps the patch) in vi.

   • ap, ci

2. Amend the commit message.

   • cia

3. Take a look at the detailed log. Scroll and search.

   • lp, cursor keys, /

4. Look up help for the checkout command. What did the -p switch do again?

   • git help ...

C: Branching and merging

1. Create a branch f-magenta, implement a show_magenta() function and a call to that function. List your branches.

   • cob, b

2. Adapt show_cyan() to call glue(inverse(cyan(...))) instead of glue(cyan(...)). Commit. Because you wanted to do it on a new f-cyan-inverse branch (instead of f-magenta), you need to switch retroactively.

   • b <branch>, q --hard, co <branch>

3. Create a branch f-cyan-underline from master, adapt show_cyan() to call glue(underline(cyan(...))) instead of glue(cyan(...)).

   • cob <branch> master

4. Visualize all branches.

   • la

5. Merge f-magenta into master.

   • co, m

6. Merge f-cyan-inverse into master without editing the commit message.

   • mo

7. List the merges without the details of the individual branches.

   • lf

8. Visualize the differences from each merge.

   • lfp

9. Delete the branches that you have merged successfully. Try deleting the f-cyan-underline branch.

   • bm, b -d

10. Restore the branches that you just deleted.

    • b <branch> <ref>

D: Conflict resolution

1. Try merging f-cyan-underline into master. Abort the merge.

   • mo, ma

2. Switch to new a backup of the f-cyan-underline branch.

   • cob

3. Try merging master into the new branch. Inspect.

   • co, mo, s, dc, conflicts, do, dt

4. Resolve the conflict by combining the changes from the conflicting branches in script.R. Do not add or commit yet -- inspect beforehand. Make sure no conflict markers like <<<<<<< remain in the file.

   • s, d

5. Commit using the default message.

   • cio

6. Switch to new a backup of the f-cyan-underline branch.

   • cob

7. Try merging master into the new branch. Inspect. How did Git resolve the conflict?

   • co, mo, s, dc, conflicts, do, dt

8. Switch to new a backup of the f-cyan-underline branch.

   • cob

9. Try merging master into the new branch, keeping the changes of the new branch. Inspect.

   • mo -X ours

10. Switch to new a backup of the f-cyan-underline branch.

    • cob

11. Try merging master into the new branch, keeping the changes of master. Inspect.

    • mo -X theirs

12. Switch to master, try merging the original f-cyan-underline branch. What happens?

    • co, mo

13. Abort the merge. Merge one of the branches where you successfully resolved the conflict into master. Explain.

    • ma, mo, la

E: Refspecs

1. Check out the f-magenta branch again. What happens?

   • co

2. Check out the parent of the f-magenta branch. What happens?

   • co, l

3. Use the log to find the SHA of an interesting commit, check it out. Explain.

   • l, co

4. Switch to master, compare with the f-magenta branch.

   • d <ref>

5. Compare the f-cyan-inverse and f-cyan-underline branches.

   • d <ref>..<ref>

6. What's new in f-cyan-inverse, compared to f-cyan-underline?

   • d <ref>...<ref>

F: Rebasing

1. Branch off of an earlier revision of master that don't include f-magenta and f-cyan-*** yet.

   • l, cob <branch> <ref>

2. Rebase f-magenta onto the new branch. Explain.

   • co, r <branch>

3. Move the new branch. Reset the tip of the new branch to the rebased f-magenta.

   • co, reset <branch>

4. Rebase f-cyan-inverse onto the new branch. Explain.

   • co, r <branch>

5. Move the new branch. Reset the tip of the new branch to the rebased f-cyan-inverse.

   • co, reset <branch>

6. Rebase f-cyan-underline onto the new branch. Explain.

   • co, r <branch>

7. Abort the rebase. Explain.

   • ra

8. Rebase f-cyan-underline onto the new branch, again.

   • r <branch>

9. Resolve the conflict, continue the rebase.

   • rc

10. Move the new branch. Reset the tip of the new branch to the rebased f-cyan-underline.

    • co, reset <branch>

11. Inspect the log. How is it different from the merging exercise?

    • l

G: Bisecting

Task: Find the commit that introduced that magenta output function.

1. Set master as "bad" revision, agree to start bisection.

   • bisect bad <branch>

2. Find an earlier revision of master that don't include f-magenta yet. Set that earlier revision as "good".

   • l, bisect good <ref>

3. Do not look at the code. Run script.R to check if there is magenta output. If yes, it's a "bad" revision, otherwise a "good" one.

   • bisect bad, bisect good

4. Rinse and repeat, until you find your bad commit. Double-check that this is indeed the change that introduces magenta output.

   • show <ref>

5. Finish bisection.

   • bisect reset

H: Not covered

1. Push/pull

2. More than one remote

3. Cherry-pick, revert, multiple cherry-pick