Git Installation Guide

# Your name and email — these end up in every commit you make
git config --global user.name "Your Name"
git config --global user.email "you@example.com"
 
# The default branch for new repositories
git config --global init.defaultBranch main
 
# The editor for commit messages
git config --global core.editor "code --wait"   # or vim, nano, ...
 
# Check what is set
git config --global --list

# Pull with rebase instead of merge commits
git config --global pull.rebase true
 
# Reuse conflict resolutions when rebasing
git config --global rerere.enabled true
 
# Show the original object when a file is renamed
git config --global diff.renames copies
 
# Prune deleted branches when fetching
git config --global fetch.prune true
 
# Use the native file system monitor on macOS and Windows
git config --global core.fsmonitor true

# 1. Generate an ed25519 key
ssh-keygen -t ed25519 -C "you@example.com"
 
# 2. Start the agent and add the key (macOS)
eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_ed25519
 
# On Linux with systemd, enable the agent once
sudo systemctl enable --now ssh-agent

# 3. Copy the public key to the host
ssh-copy-id -i ~/.ssh/id_ed25519.pub you@server
 
# 4. Test it
ssh -T git@github.com

Host github.com
  IdentityFile ~/.ssh/id_ed25519_github
  AddKeysToAgent yes
 
Host gitlab.com
  IdentityFile ~/.ssh/id_ed25519_gitlab

# Linux, macOS and Windows with Git Credential Manager installed
git config --global credential.helper manager
 
# macOS only — the system keychain
git config --global credential.helper osxkeychain
 
# Windows only — the Windows Credential Manager
git config --global credential.helper manager

# Check which helper is active
git config --global credential.helper
git credential fill   # type protocol=https, host=github.com and press Ctrl-D

# Use the SSH key format
git config --global gpg.format ssh
 
# The key to sign with
git config --global user.signingkey ~/.ssh/id_ed25519.pub
 
# Sign every commit automatically
git config --global commit.gpgsign true
 
# And every tag
git config --global tag.gpgsign true

# Verify a signature
git log --show-signature -1

# Start a repository and commit
git init
git add .
git commit -m "Initial commit"
 
# Branching — the modern commands
git switch -c feature/login        # create and switch
git switch main                     # switch back
git switch -                        # switch to the previous branch
git branch -d feature/login        # delete a merged branch
 
# Undo changes
git restore file.txt                # discard unstaged changes
git restore --staged file.txt       # unstage
git restore --source=HEAD file.txt  # discard changes to a file
git commit --amend                  # fix the last commit
 
# Unstage
git reset HEAD file.txt
 
# See what changed
git status
git diff
git diff --staged
git log --oneline --graph --decorate
 
# Pull with rebase
git pull --rebase
 
# Sync a branch with the main branch
git rebase main
# or merge the other way
git merge main
 
# Undo a merge or rebase
git reset --hard ORIG_HEAD
 
# Stash work in progress
git stash push -m "wip"
git stash list
git stash pop
 
# Worktrees — a second checkout of the same repository
git worktree add ../myapp-feature feature/login