Git for DevOps Engineers – The Complete Guide

git init

mkdir ansible-playbooks
cd ansible-playbooks
git init
# Output: Initialized empty Git repository in /ansible-playbooks/.git/

git clone <repository-url>
git clone <repository-url> <target-folder-name>

git clone https://github.com/org/terraform-infra.git
git clone https://github.com/org/terraform-infra.git my-infra

git status

On branch feature/add-nginx-config
Changes not staged for commit:
  modified:   nginx/nginx.conf

Untracked files:
  nginx/ssl.conf

git add <filename>         # Stage a specific file
git add .                  # Stage all changed files
git add -p                 # Stage changes interactively (hunk by hunk)

git add Dockerfile

git add .

git commit -m "your message here"
git commit -am "message"      # Stage tracked files and commit in one step

git commit -m "feat: update nginx deployment replicas to 3 for HA"

feat: add Redis cache configuration
fix: correct wrong port in service manifest
chore: update .gitignore for terraform state files
docs: add runbook for database failover

git log                        # Full history
git log --oneline              # Compact one-line view
git log --oneline --graph      # Visual branch tree
git log --oneline -10          # Last 10 commits
git log --author="Alice"       # Filter by author
git log -- path/to/file        # History of a specific file

git log --oneline --graph --all
# Output:
# * a3f1c2d (HEAD -> main) feat: add Prometheus scrape config
# * b7e90ca fix: correct Grafana data source URL
# * 1d4e8f0 chore: update terraform provider versions

git branch                     # List all local branches
git branch -a                  # List all branches (local + remote)
git branch feature/my-feature  # Create a new branch
git branch -d feature/done     # Delete a branch (safe — only if merged)
git branch -D feature/force    # Force delete a branch

git branch -a
# Output:
# * main
#   feature/add-github-actions
#   remotes/origin/main
#   remotes/origin/release/v1.2

git checkout branch-name           # Old way
git switch branch-name             # New way (recommended)
git switch -c feature/new-branch   # Create and switch in one step
git checkout -b feature/new-branch # Old equivalent

git switch -c feature/add-helm-chart
# Output: Switched to a new branch 'feature/add-helm-chart'

git pull
git pull origin main           # Pull from a specific remote and branch
git pull --rebase origin main  # Pull using rebase instead of merge

git switch main
git pull origin main
# Always pull before you start coding to avoid conflicts later.

git fetch
git fetch origin
git fetch --all        # Fetch from all remotes

git fetch origin
git log HEAD..origin/main --oneline
# Shows what commits are on remote that you don't have yet

git push
git push origin main                      # Push to a specific remote branch
git push -u origin feature/my-feature     # Push and set upstream tracking
git push --force-with-lease               # Force push safely (preferred over --force)

git push -u origin feature/add-argo-workflow

git merge feature/branch-name
git merge --no-ff feature/branch-name    # Always create a merge commit
git merge --squash feature/branch-name   # Squash all commits into one

git switch main
git pull origin main
git merge feature/add-monitoring-stack
git push origin main

git rebase main                  # Rebase current branch on top of main
git rebase -i HEAD~5             # Interactive rebase — edit last 5 commits

git switch feature/add-fluentd
git rebase main
# Your commits are now replayed on top of the latest main

git rebase -i HEAD~3
# Opens an editor where you can squash, rename, or reorder commits

git stash                          # Stash current changes
git stash push -m "work in progress on nginx config"   # Stash with a label
git stash list                     # See all stashes
git stash pop                      # Apply latest stash and remove it
git stash apply stash@{2}          # Apply a specific stash without removing it
git stash drop stash@{0}           # Delete a stash

# You're midway through editing a Terraform file
git stash push -m "wip: vpc peering changes"

# Switch to fix the urgent bug
git switch hotfix/fix-lb-timeout
# ... make fix, commit, push ...

# Come back and restore your work
git switch feature/vpc-peering
git stash pop

git diff                          # Unstaged changes vs last commit
git diff --staged                 # Staged changes vs last commit
git diff main..feature/my-branch  # Difference between two branches
git diff commit1 commit2          # Difference between two commits

git diff --staged

git reset --soft HEAD~1    # Undo last commit, keep changes staged
git reset --mixed HEAD~1   # Undo last commit, keep changes unstaged (default)
git reset --hard HEAD~1    # Undo last commit and DISCARD all changes (destructive)
git reset HEAD filename    # Unstage a specific file

git reset --soft HEAD~1
# Commit is removed, but your file changes are still staged

git revert <commit-hash>
git revert HEAD            # Revert the latest commit

git log --oneline
# a3f1c2d fix: wrong memory limit in deployment

git revert a3f1c2d
# Creates a new commit that undoes the change
git push origin main

git tag                           # List all tags
git tag v1.0.0                    # Create a lightweight tag
git tag -a v1.0.0 -m "Release 1.0.0 — initial stable release"  # Annotated tag (preferred)
git push origin v1.0.0            # Push a specific tag
git push origin --tags            # Push all tags

git tag -a v2.3.1 -m "Release v2.3.1 — security patch for CVE-2026-1234"
git push origin v2.3.1

git remote -v                            # List remotes with URLs
git remote add origin <url>              # Add a remote called "origin"
git remote set-url origin <new-url>      # Change remote URL
git remote remove origin                 # Remove a remote

git remote set-url origin https://gitlab.company.com/infra/terraform-aws.git
git remote -v
# origin  https://gitlab.company.com/infra/terraform-aws.git (fetch)
# origin  https://gitlab.company.com/infra/terraform-aws.git (push)

git cherry-pick <commit-hash>
git cherry-pick abc123 def456     # Cherry-pick multiple commits

# Fix was committed on main with hash a1b2c3d
git switch release/v1.5
git cherry-pick a1b2c3d
git push origin release/v1.5

git bisect start
git bisect bad                    # Current commit is broken
git bisect good v1.0.0            # This older tag was working
# Git checks out a middle commit — you test and mark it:
git bisect good                   # or
git bisect bad
# Repeat until Git identifies the first bad commit
git bisect reset                  # End the session

git bisect start
git bisect bad                    # HEAD is broken
git bisect good v2.1.0            # v2.1.0 was stable
# Git will help you narrow it down in ~7 steps for 100 commits

git blame filename
git blame -L 10,20 filename       # Show only lines 10–20

git blame Jenkinsfile
# Output shows commit hash, author, date, and line content for each line

# Daily Workflow
git switch main && git pull          # Start from the latest
git switch -c feature/my-task        # Create a new branch
# ... make your changes ...
git status                           # Check what changed
git diff --staged                    # Review staged changes
git add .                            # Stage changes
git commit -m "feat: describe change" # Save a snapshot
git push -u origin feature/my-task   # Push to remote
# Open a Pull Request / Merge Request on GitHub/GitLab

# Keeping your branch up to date
git fetch origin
git rebase origin/main

# Quick fix on production
git stash
git switch hotfix/urgent-fix
# Fix, commit, push
git switch feature/my-task
git stash pop

# Set your identity (required before first commit)
git config --global user.name "Your Name"
git config --global user.email "you@company.com"

# Set default branch name to main
git config --global init.defaultBranch main

# Set VS Code as default editor
git config --global core.editor "code --wait"

# Enable colored output
git config --global color.ui auto

# View all your config
git config --global --list

# Set up aliases for common commands
git config --global alias.st status
git config --global alias.co checkout
git config --global alias.lg "log --oneline --graph --all"