nexus, index source

git and GitHub

“If it’s not in git it doesn’t exist.” -Chris Simmons

The levels of git

• Level 0: The gh-pages gotcha (multi-branch repos)
• Level 1: Basics — the six commands you need
• Level 2: Resolving conflicts, stashing
• Level 3: GitHub integration, branching, pull requests, actions

Level 0: The gh-pages gotcha

This applies to repos like nexus that use GitHub Pages on a gh-pages branch. The default git clone only gives you main. To get the gh-pages content:

cd ~
git clone -b gh-pages https://github.com/robfatland/nexus nexus-pages

Alternatively, use git worktree to have both branches checked out simultaneously:

git -C ~/nexus worktree add ~/nexus-pages gh-pages

This creates a second working directory for the gh-pages branch while sharing the same underlying repo history.

Level 1: Basics

A GitHub account has an organization name — I’ll use lemon — so we have https://github.com/lemon. Within that we create repositories, e.g. https://github.com/lemon/ocean.

Create and clone a repo

cd ~
git clone https://github.com/lemon/ocean
cd ocean

The daily workflow: pull, add, commit, push

cd ~/ocean
git pull --rebase
git add .
git commit -m 'a comment on what I modified just now'
git push

Why git pull --rebase first? If you’ve committed changes from another machine, the GitHub version may be “ahead” of your local copy. Pulling first brings in those changes so your push merges cleanly. If git pull --rebase generates an error, reverse with git rebase --abort. See this YouTube video for more on why --rebase.

Synching multiple repos with a script

For multiple repos, a shell script saves time:

# pull.sh
echo ant
cd ~/ant; git pull
cd ~

Run with: source pull.sh

Level 2: Resolving conflicts

When git pull encounters conflicting changes, git marks the conflicts in the affected files. Open them, look for <<<<<<<, =======, >>>>>>> markers, resolve manually, then:

git add <resolved-file>
git commit -m 'resolved merge conflict'
git push

Stashing

If you have uncommitted changes and need to pull:

git stash
git pull --rebase
git stash pop

Level 3: Advanced topics

• Automatic authentication: git config --global credential.helper store, then push once with your token
• Large data: Keep repos under ~100MB. Use .gitignore to exclude data files.
• Undoing mistakes: git reset --hard HEAD (discard uncommitted changes) or git reset --hard HEAD~1 (undo last commit)
  • HEAD~n means n commits back
• Branching and pull requests: For collaborative workflows (not covered here yet)

The “nuclear option” for recovery

Sometimes edits and pulls and pushes cross wires. A pragmatic fix:

1. Rename your local directory: mv myrepo myrepo_oops (it’s now just a “source bin”, no longer a git repo)
2. Clone fresh from GitHub: git clone https://github.com/lemon/myrepo
3. Copy your good changes from myrepo_oops back into the fresh clone
4. git add . && git commit -m 'recovered' && git push

Conversely if GitHub is busted: Create a new repo on GitHub, clone it locally, copy in your good local files, push.

This doesn’t touch 94% of git’s powerful features like rollbacks. It’s a basic get-started toolkit.