Quick Reference Guide

# Setup and remotes
git init                              # new repository
git clone <url>                       # copy a remote repository
git remote -v                         # list remotes
git remote add origin <url>           # add a remote

# Everyday work
git status                            # working-tree status
git add <path>                        # stage a file (git add -p: stage hunks interactively)
git commit -m "message"               # commit staged changes
git commit --amend                    # rewrite the last (unpushed) commit
git fetch --prune                     # update remote-tracking refs, drop deleted ones
git pull --rebase                     # fetch + rebase local commits on top
git push -u origin <branch>           # push and set upstream

# Branches
git branch                            # list local branches (-a: include remote)
git switch <branch>                   # change branch
git switch -c <branch>                # create and switch
git merge <branch>                    # merge into current branch
git rebase <branch>                   # replay current branch onto <branch>
git branch -d <branch>                # delete a merged branch (-D: force)
git push origin --delete <branch>     # delete a remote branch

# Inspecting history
git log --oneline --graph --all       # compact history graph
git diff                              # unstaged changes
git diff --staged                     # staged changes
git show <commit>                     # one commit's diff and metadata
git blame <file>                      # last change per line
git log -S "<text>"                   # commits that added/removed <text>

# Undoing
git restore <file>                    # discard unstaged changes to a file
git restore --staged <file>           # unstage, keep changes
git reset --soft HEAD~1               # undo last commit, keep changes staged
git reset HEAD~1                      # undo last commit, keep changes unstaged
git reset --hard HEAD~1               # undo last commit, discard changes (destructive)
git revert <commit>                   # new commit that inverts <commit> (safe on shared branches)
git push --force-with-lease           # force-push only if the remote hasn't moved
git stash / git stash pop             # shelve and restore uncommitted work

# Power tools
git cherry-pick <commit>              # apply one commit onto the current branch
git bisect start <bad> <good>         # binary-search for a regression
git reflog                            # every position HEAD has held (recovery)
git worktree add ../<dir> <branch>    # second working tree on another branch

# Containers
docker run -d --name <n> -p 8080:80 <image>   # detached, publish port
docker run --rm -it <image> sh                # throwaway interactive shell
docker ps / docker ps -a                      # running / all containers
docker logs -f <container>                    # follow logs
docker exec -it <container> sh                # shell into a running container
docker stop <container> && docker rm <container>
docker inspect <container>                    # full JSON config and state
docker stats                                  # live CPU/memory usage

# Images
docker build -t <name>:<tag> .                # build from ./Dockerfile (BuildKit)
docker buildx build --platform linux/amd64,linux/arm64 -t <name>:<tag> --push .
docker images                                 # list images
docker pull <image> / docker push <image>
docker tag <source> <target>
docker rmi <image>

# Compose (v2 plugin syntax)
docker compose up -d                          # start services detached
docker compose up -d --build                  # rebuild then start
docker compose ps                             # service status
docker compose logs -f <service>              # follow a service's logs
docker compose exec <service> sh              # shell into a service
docker compose down                           # stop and remove (add -v to drop volumes)

# Housekeeping
docker system df                              # disk usage by type
docker system prune                           # remove stopped containers, dangling images, unused networks
docker volume ls / docker network ls

# Context and cluster
kubectl config get-contexts                   # available clusters/users
kubectl config use-context <ctx>              # switch cluster
kubectl config set-context --current --namespace=<ns>
kubectl get nodes -o wide                     # nodes with IPs and versions

# Reading resources
kubectl get pods -A                           # all namespaces
kubectl get deploy,svc,ingress -n <ns>
kubectl describe pod <pod>                    # events, probes, scheduling
kubectl get pod <pod> -o yaml                 # live spec and status
kubectl get events --sort-by=.lastTimestamp
kubectl explain deployment.spec.strategy      # built-in schema docs

# Changing resources
kubectl apply -f <file-or-dir>                # declarative create/update
kubectl diff -f <file>                        # preview what apply would change
kubectl delete -f <file>
kubectl scale deploy/<name> --replicas=3
kubectl set image deploy/<name> <container>=<image>:<tag>
kubectl rollout status deploy/<name>
kubectl rollout undo deploy/<name>
kubectl rollout restart deploy/<name>         # re-create pods with the same spec

# Debugging
kubectl logs <pod> [-c <container>] [-f] [--previous]
kubectl exec -it <pod> -- sh
kubectl debug -it <pod> --image=busybox --target=<container>   # ephemeral debug container
kubectl port-forward svc/<name> 8080:80
kubectl top pod                               # requires metrics-server

# Identity and auth
aws configure sso                             # set up an IAM Identity Center profile
aws sso login --profile <p>
aws sts get-caller-identity                   # who am I? (first thing to check)

# S3
aws s3 ls s3://<bucket>/<prefix>/
aws s3 cp <file> s3://<bucket>/<key>
aws s3 sync ./dir s3://<bucket>/dir --delete  # mirror a directory
aws s3 rm s3://<bucket>/<key> [--recursive]
aws s3 presign s3://<bucket>/<key> --expires-in 3600

# EC2
aws ec2 describe-instances \
  --filters Name=instance-state-name,Values=running \
  --query 'Reservations[].Instances[].[InstanceId,InstanceType,PrivateIpAddress]' \
  --output table
aws ec2 start-instances --instance-ids <id>
aws ec2 stop-instances --instance-ids <id>
aws ssm start-session --target <instance-id>  # shell without SSH keys or open ports

# IAM
aws iam list-roles --query 'Roles[].RoleName'
aws iam get-role --role-name <name>

# Lambda
aws lambda list-functions
aws lambda invoke --function-name <name> --payload '{}' \
  --cli-binary-format raw-in-base64-out out.json
aws lambda update-function-code --function-name <name> --zip-file fileb://function.zip

# CloudFormation
aws cloudformation deploy --stack-name <name> --template-file template.yaml \
  --capabilities CAPABILITY_IAM              # create or update via change set
aws cloudformation describe-stack-events --stack-name <name>
aws cloudformation delete-stack --stack-name <name>

# Logs
aws logs tail /aws/lambda/<name> --follow

# Setup
terraform init                         # download providers/modules, configure backend
terraform init -upgrade                # upgrade within version constraints
terraform fmt -recursive               # canonical formatting (-check in CI)
terraform validate                     # static validation

# Plan and apply
terraform plan -out=tfplan             # preview and save the plan
terraform apply tfplan                 # apply exactly the saved plan
terraform plan -var-file=prod.tfvars
terraform apply -replace=<addr>        # force re-creation (replaces "taint")
terraform apply -refresh-only          # reconcile state with reality (replaces "refresh")
terraform plan -target=<addr>          # limit scope (exceptional use only)
terraform destroy

# State
terraform state list
terraform state show <addr>
terraform state mv <src> <dst>         # prefer a `moved` block in code
terraform state rm <addr>              # prefer a `removed` block in code
terraform force-unlock <lock-id>

# Import (prefer config-driven `import` blocks, Terraform 1.5+)
terraform import <addr> <id>
terraform plan -generate-config-out=generated.tf

# Inspection
terraform output [-json] [<name>]
terraform console                      # evaluate expressions
terraform graph | dot -Tsvg > graph.svg
terraform providers
terraform test                         # run *.tftest.hcl tests (1.6+)

# Environment variables
export TF_LOG=DEBUG TF_LOG_PATH=tf.log
export TF_VAR_region=us-east-1         # sets var.region