full lecture notes

README.md

@@ -15,3 +15,40 @@
 
 — Lars Wirzenius (Linux kernel developer)
 
+## Warm-Up
+- how to start a repo from scratch?
+    - `git init` local method
+    - on an online forge (GitHub, GitLab, …): `git clone`
+- how to revert mistakes?
+    - before commit:
+      - `git restore <file>` [discard changes in the working directory] __changes files__
+      - `git restore --staged <file>` [unstage changes ➔ opposite of `git add <file>`, does not modify the working directory]
+    - after commit:
+      - `git revert <commit>` [creates a new commit, modifies the working directory]
+      - `git reset <commit>` [only reset the HEAD pointer, does not modify the working directory] __rewrites history__ ➔ can not be used if you have already pushed to some remote
+      - `git reset --hard <commit>` [reset HEAD and modify working directory] __rewrites history__ and __changes files__ ➔ can not be used if you have already pushed to some remote
+- how to *move* the whole working directory to a specific point in history?
+    - `git checkout <commit>` ➔ `DETACHED HEAD` problem, __changes__ __files__
+    - interaction with branches: `git branch <branch_name>` + `git switch <branch_name>` 
+- how to copy a file from a different branch:
+    - `git checkout <branch> <file>` ➔ the file is staged automatically
+    - `git restore --source=<branch> <file` ➔ the file is not staged
+- `git gui`: building commits along the way interactively (for the *mess around* type of workflows)
+- check out these [sketches](git-commands-visualizations.pdf) for a graphical visualization of git commands!
+
+## Workflows
+Look at the [sketches](workflow_sketches.pdf)
+
+1. **lone scientist local** ➔  working alone in the cellar without Internet (local git)
+2. **lone scientist remote** ➔ uploading their software to the Internet in the hope it can be useful for other people (local git + one personal repo on a git-forge)
+3. **research group** ➔ sharing one software project with some other befriended scientist working in a different place (local git + group repo on a git-forge + permissions)
+4. **fully distributed software development** ➔ using the most typical open source software workflows as used by numpy, scipy, sklearn, etc. (like above + we don't trust our contributors, i.e. work strictly with forks)
+
+## The Open Source workflow
+- remotes: `git pull <from_where> <what>`, `git push <where> <what>`, `git fetch <from_where> <what>`, `git merge <another_branch>`
+- git-forge: forks, branches and PRs: notice the difference between `fork` and `clone`!!!
+- strategies for keeping your fork up-to-date: your `main`, origin's and upstream's `main`, short-lived and long-lived topic branches
+- a more thorough and detailed explanation can be found on the [SciPy Contributor's Guide](https://docs.scipy.org/doc/scipy/dev/gitwash/gitwash.html). This guide can be adapted to your own needs, see [gitwash](https://github.com/matthew-brett/gitwash).
+- GitHub and GitLab are just options (git≠GitHub): there are many git-forges out there, both installable on premises (e.g. [forgejo](https://forgejo.org/)) ) or as an online service for free and open source software (e.g. [codeberg](https://codeberg.org/)
+
+