Shell, filesystem, filtering, permissions, package managers, PowerShell, and Command Prompt essentials.
01 — Shell Essentials
Where Am I? / Help
pwd
Print current directory.
whoami
Show current user.
echo $SHELL
Show active Unix shell.
command -v node
Find an executable in PATH.
man ls
Open Unix manual page.
cmd --help
Most CLIs: show built-in help.
history
Recent shell commands.
clear
Clear terminal screen.
Files & Folders
ls -la
List all files with details.
cd path
Change directory.
cd ..
Move up one directory.
mkdir -p a/b
Create nested directories.
touch file.txt
Create empty file / update time.
cp file copy
Copy file.
cp -R src dst
Copy directory recursively.
mv old new
Move or rename.
rm file
Delete file.
rm -rf folder
DOUBLE-CHECK path. Force-delete directory tree.
Read & Inspect
cat file
Print entire small file.
less file
Scrollable file viewer.
head -n 20 file
First 20 lines.
tail -n 20 file
Last 20 lines.
tail -f app.log
Follow a growing log.
wc -l file
Count lines.
du -sh folder
Human-readable folder size.
df -h
Disk free space.
Search & Filter
grep -n "text" file
Find text + line numbers.
grep -Rni "text" .
Recursive, case-insensitive search.
find . -name "*.js"
Find files by name pattern.
find . -type f -mtime -1
Files modified in last day.
sort file
Sort lines.
uniq -c
Count adjacent duplicate lines.
cut -d, -f1 file.csv
Select delimited field.
xargs command
Build command args from stdin.
Pipes & Operators
a | b
Pipe stdout of a into b.
a > file
Overwrite file with stdout.
a >> file
Append stdout to file.
a 2> err.log
Redirect stderr.
a 2>&1
Send stderr to stdout.
a && b
Run b only if a succeeds.
a || b
Run b only if a fails.
a ; b
Run sequentially regardless.
$(command)
Substitute command output.
VAR=value cmd
Set env var for one command.
PowerShell Essentials
Get-Location
Current directory (pwd alias).
Get-ChildItem
List items (ls alias).
Set-Location path
Change directory (cd alias).
New-Item -ItemType Directory x
Create folder.
Copy-Item a b -Recurse
Copy file/folder.
Move-Item a b
Move / rename.
Remove-Item x -Recurse
Delete tree; inspect path first.
Get-Content file
Print file.
Select-String "text" file
Search text.
Get-Command node
Locate command.
Get-Process
List processes.
Stop-Process -Id 1234
Stop process by PID.
$env:NAME
Read env variable.
$env:NAME="value"
Set env variable for session.
OS Package Managers
brew update
macOS: refresh Homebrew metadata.
brew install git
macOS: install package.
brew upgrade
macOS: upgrade installed formulae.
brew list
macOS: list installed packages.
sudo apt update
Debian/Ubuntu: refresh indexes.
sudo apt install git
Debian/Ubuntu: install package.
winget search git
Windows: search packages.
winget install Git.Git
Windows: install package.
Command Prompt: Common Basics
dir
List directory.
cd path
Change directory.
mkdir folder
Create folder.
copy a b
Copy file.
move a b
Move/rename.
del file
Delete file.
type file
Print file.
where node
Locate executable.
set NAME=value
Set env var for session.
cls
Clear screen.
NOTE
For development on Windows, PowerShell or WSL usually gives a richer workflow than classic cmd.exe.
Version control, GitHub CLI, SSH, HTTP/network checks, and VS Code terminal commands.
02 — Git, GitHub & Developer Tools
Git: Start & Config
git --version
Check Git version.
git config --global user.name "Name"
Set commit author name.
git config --global user.email "you@example.com"
Set commit email.
git init
Create repository in current folder.
git clone URL
Clone remote repository.
git status
Show branch + working tree status.
Stage & Commit
git add file
Stage one file.
git add .
Stage changes under current directory.
git diff
Unstaged changes.
git diff --staged
Staged changes.
git commit -m "message"
Create commit.
git commit --amend
Replace most recent commit.
Branches
git branch
List local branches.
git switch branch
Switch branch.
git switch -c feature
Create + switch branch.
git merge feature
Merge feature into current branch.
git branch -d feature
Delete merged local branch.
git branch -D feature
Force-delete local branch.
Inspect History
git log --oneline
Compact history.
git log --graph --decorate --all --oneline
Visual branch graph.
git show COMMIT
Inspect a commit.
git blame file
Show line-by-line authorship.
Remotes & Sync
git remote -v
List remote URLs.
git fetch
Download remote refs; no merge.
git pull
Fetch + integrate current branch.
git push
Push current branch.
git push -u origin feature
Push + set upstream.
git push --tags
Push tags.
git tag -a v1.0.0 -m "release"
Create annotated tag.
Undo Safely
git restore file
Discard unstaged file changes.
git restore --staged file
Unstage; keep file changes.
git revert COMMIT
New commit that reverses a commit.
git reset --soft HEAD~1
Move HEAD back; keep changes staged.
git reset --hard HEAD~1
Destructive: discard commit + local changes.
git stash
Temporarily shelve changes.
git stash list
List stashes.
git stash pop
Reapply + remove latest stash.
GitHub CLI (gh)
gh auth login
Authenticate GitHub CLI.
gh repo clone OWNER/REPO
Clone GitHub repo.
gh repo create
Create repository interactively.
gh pr create
Open pull request.
gh pr checkout 123
Check out PR #123.
gh pr view --web
Open current PR in browser.
gh issue list
List issues.
gh workflow list
List Actions workflows.
NOTE
GitHub CLI is a separate install. Run
gh help or gh <command> --help for current options.
SSH & File Transfer
ssh user@host
Open SSH session.
ssh-keygen -t ed25519 -C "email"
Create modern SSH key.
ssh-add ~/.ssh/id_ed25519
Add private key to agent.
scp file user@host:/path
Copy file over SSH.
scp -r dir user@host:/path
Copy directory recursively.
rsync -av src/ host:/dest/
Efficient recursive sync.
ssh -T git@github.com
Test GitHub SSH auth.
HTTP / Network Checks
curl URL
GET a URL.
curl -I URL
Headers only.
curl -L URL
Follow redirects.
curl -X POST URL -H "Content-Type: application/json" -d '{"x":1}'
POST JSON.
ping host
Basic reachability.
dig example.com
DNS lookup (Unix).
nslookup example.com
DNS lookup (cross-platform).
lsof -i :5173
Find Unix process on port.
curl localhost:3000
Quick local-server test.
VS Code Terminal CLI
code .
Open current folder.
code file.js
Open file.
code -n .
Open in new window.
code --version
Show VS Code version.
code --list-extensions
List extensions.
code --install-extension ID
Install extension by ID.
Ctrl+`
Toggle integrated terminal (Win/Linux).
Cmd+`
Toggle integrated terminal (macOS).
Ctrl+Shift+P / Cmd+Shift+P
Command Palette.
Node.js, npm, package managers, TypeScript, linting, testing, semver, and dependency troubleshooting.
03 — Node.js & JavaScript Tooling
Node & npm Basics
node -v
Node.js version.
npm -v
npm CLI version.
node file.js
Run JavaScript file.
node --watch server.js
Restart on file changes.
node -e "console.log(1+1)"
Run one-line JavaScript.
npm init -y
Create package.json with defaults.
npm install
Install dependencies from package.json.
npm ci
Clean, lockfile-exact install; ideal CI.
npm install package
Add production dependency.
npm install -D package
Add devDependency.
npm uninstall package
Remove dependency.
npm Inspect & Maintain
npm outdated
Show outdated dependencies.
npm update
Update within allowed semver ranges.
npm audit
Report known dependency issues.
npm audit fix
Apply compatible security updates.
npm ls
Show installed dependency tree.
npm explain package
Why a package is installed.
npm view package version
Registry package info.
npm cache verify
Verify/compact npm cache.
npm Scripts
npm run
List available package scripts.
npm run dev
Run dev script.
npm test
Run test script.
npm run build
Run build script.
npm start
Run start script.
npm run name -- --flag
Pass args through to script.
npm exec -- eslint .
Run package binary via npm.
npx package args
Run local/temporary package binary.
NVM: Node Versions
nvm install --lts
Install latest LTS Node.
nvm use --lts
Use LTS Node in shell.
nvm install 22
Install a major version.
nvm use 22
Switch active Node version.
nvm ls
List installed Node versions.
nvm alias default lts/*
Default future shells to LTS.
NOTE
nvm commands require nvm (or nvm-windows on Windows). The two projects differ slightly.
Package Manager Equivalents
TypeScript
npx tsc --init
Create tsconfig.json.
npx tsc
Compile project.
npx tsc --noEmit
Type-check without output.
npx tsc -w
Watch + recompile.
npx tsx file.ts
Run TS directly when tsx is installed.
Lint & Format
npx eslint .
Lint project.
npx eslint . --fix
Auto-fix safe lint issues.
npx prettier . --check
Check formatting.
npx prettier . --write
Rewrite files to formatter rules.
Testing
npx vitest
Run Vitest in watch mode.
npx vitest run
Single Vitest run.
npx jest
Run Jest.
npx playwright test
Run Playwright tests.
npx playwright test --ui
Open Playwright UI mode.
npx playwright show-report
Open HTML report.
Semver Quick Read
1.2.3
major.minor.patch.
^1.2.3
Allow compatible minor/patch updates.
~1.2.3
Allow patch updates within 1.2.x.
1.2.3
Exact version when no range operator.
latest
Registry distribution tag; not a range.
When Installs Are Weird
npm ci
First choice when lockfile is valid.
npm cache verify
Check cache before deleting things.
rm -rf node_modules && npm install
Rebuild local dependency tree.
npm install package@latest
Explicitly request current latest tag.
NOTE
Avoid casually deleting lockfiles: they preserve reproducible dependency versions and often belong in source control.
Frontend and full-stack JavaScript framework CLIs, environment variables, project flow, and security habits.
04 — Frontend & Full-Stack Framework CLIs
Frontend Framework Quick Starts
Express / Node API
npm init -y
Start package.json.
npm install express
Install Express.
node server.js
Run server entry file.
node --watch server.js
Built-in file watch restart.
npx express-generator app
Optional Express generator scaffold.
NestJS
npx @nestjs/cli@latest new app
Scaffold Nest application.
npm run start:dev
Watch-mode dev server.
npx nest g module users
Generate module.
npx nest g controller users
Generate controller.
npx nest g service users
Generate service.
npx nest g resource users
Generate CRUD resource workflow.
Prisma ORM
npx prisma init
Initialize Prisma project.
npx prisma migrate dev --name init
Create + apply dev migration.
npx prisma generate
Generate Prisma Client.
npx prisma studio
Open database GUI.
npx prisma db pull
Introspect existing database.
npx prisma db push
Push schema without migration history.
npx prisma migrate deploy
Apply pending migrations in deploy.
NOTE
Prisma v7 no longer guarantees that migrate dev will also run prisma generate; run generate explicitly when needed.
Environment Variables
export API_URL=http://localhost:3000
Set Unix env var for shell.
API_URL=x npm run dev
Set Unix env var for one command.
$env:API_URL="x"
PowerShell: set for session.
node --env-file=.env server.js
Node: load env file at runtime.
printenv API_URL
Unix: print one env var.
Get-ChildItem Env:
PowerShell: list env vars.
Common JavaScript Project Flow
Typical project start-up flow
Use this sequence when opening an existing JavaScript project with a valid lockfile and an environment template.
Example
git clone URL
cd project
npm ci
cp .env.example .env
npm run dev
npm test
npm run build
git statusSecurity Habits
.env
Keep secrets out of committed source.
.gitignore
Ignore local secrets/build artifacts.
npm audit
Review dependency advisories.
--help
Read current CLI options before destructive operations.
tokens/keys
Use secret managers or environment variables; never paste into public repos.
Database shells and essential commands plus Python, .NET, and Java build/runtime tooling.
05 — Databases, SQL Shells & Other Runtimes
PostgreSQL / psql
psql -U postgres
Connect as user postgres.
psql -d appdb
Connect to database.
\l
List databases.
\c appdb
Connect/switch database.
\dt
List tables.
\d users
Describe table.
\q
Quit psql.
createdb appdb
Create database from OS shell.
dropdb appdb
DESTRUCTIVE. Drop database.
pg_dump appdb > backup.sql
Plain SQL backup.
MySQL Client
mysql -u root -p
Connect and prompt for password.
SHOW DATABASES;
List databases.
USE appdb;
Select database.
SHOW TABLES;
List tables.
DESCRIBE users;
Describe table.
exit
Quit client.
mysqldump -u root -p appdb > backup.sql
SQL backup.
SQLite
sqlite3 app.db
Open/create database file.
.tables
List tables.
.schema users
Show table schema.
.headers on
Show column headings.
.mode column
Readable column output.
.quit
Exit sqlite3.
SQL Essentials
SELECT * FROM users;
Read rows.
SELECT ... WHERE ...;
Filter rows.
INSERT INTO t (...) VALUES (...);
Create row.
UPDATE t SET x=... WHERE ...;
Change rows; WHERE matters.
DELETE FROM t WHERE ...;
Delete rows; WHERE matters.
CREATE TABLE ...;
Create table.
ALTER TABLE ...;
Change table structure.
DROP TABLE ...;
DESTRUCTIVE. Delete table.
BEGIN; / COMMIT;
Start / save transaction.
ROLLBACK;
Undo uncommitted transaction.
MongoDB Shell
mongosh
Open MongoDB shell.
show dbs
List databases.
use appdb
Switch/create-on-use database.
show collections
List collections.
db.users.find()
Query users collection.
db.users.findOne({email:"a@b.com"})
Find one matching document.
db.users.countDocuments()
Count documents.
Redis CLI
redis-cli
Open Redis CLI.
PING
Server health check.
SET key value
Store string.
GET key
Read string.
DEL key
Delete key.
SCAN 0
Iterate keys safely.
TTL key
Seconds until expiration.
Python Environments & pip
python3 --version
Check Python version.
python3 -m venv .venv
Create virtual environment.
source .venv/bin/activate
Activate on macOS/Linux.
.venv\Scripts\Activate.ps1
Activate in PowerShell.
python -m pip install -U pip
Upgrade pip in active Python.
python -m pip install package
Install package.
python -m pip install -r requirements.txt
Install pinned requirements.
python -m pip freeze > requirements.txt
Record environment packages.
deactivate
Leave virtual environment.
Python Web Quick Starts
python app.py
Run a Python entry file.
flask --app app run --debug
Flask dev server.
django-admin startproject site
Create Django project.
python manage.py runserver
Django dev server.
python manage.py makemigrations
Create Django migrations.
python manage.py migrate
Apply Django migrations.
pytest
Run pytest suite.
.NET CLI
dotnet --info
SDK/runtime information.
dotnet new webapi -n Api
Create Web API project.
dotnet restore
Restore NuGet packages.
dotnet build
Compile project.
dotnet run
Run application.
dotnet watch
Watch + rerun.
dotnet test
Run tests.
dotnet add package NAME
Add NuGet package.
Java / Maven / Gradle
java --version
Java runtime version.
javac File.java
Compile Java source.
mvn -v
Maven version.
mvn clean test
Clean + run tests.
mvn spring-boot:run
Run Spring Boot via Maven.
./gradlew build
Gradle wrapper build.
./gradlew test
Gradle wrapper tests.
./gradlew bootRun
Run Spring Boot via Gradle.
Docker, Compose, Kubernetes, cloud CLI checks, common ports, troubleshooting, and high-risk commands.
06 — Docker, Cloud & Troubleshooting
Docker Essentials
docker --version
Docker CLI version.
docker info
Engine/system information.
docker pull image
Download image.
docker images
List local images.
docker ps
Running containers.
docker ps -a
All containers.
docker run --rm -it image sh
Temporary interactive container.
docker run -p 3000:3000 image
Map host:container port.
docker build -t app:dev .
Build image from Dockerfile.
docker exec -it NAME sh
Shell inside running container.
docker logs -f NAME
Follow container logs.
docker stop NAME
Stop container.
docker rm NAME
Remove stopped container.
Docker Cleanup
docker volume ls
List volumes.
docker network ls
List networks.
docker system df
Disk used by Docker.
docker image prune
Remove dangling images.
docker container prune
Remove stopped containers.
docker system prune
Broad cleanup; review prompt carefully.
Docker Compose
docker compose up
Create/start + attach.
docker compose up -d
Start in background.
docker compose up --build
Build then start.
docker compose ps
List project containers.
docker compose logs -f
Follow service logs.
docker compose exec api sh
Shell in service container.
docker compose build
Build/rebuild services.
docker compose build --no-cache
Rebuild without cache.
docker compose pull
Pull service images.
docker compose down
Stop/remove project containers/network.
docker compose down -v
High risk: also remove named volumes/data.
Kubernetes Basics
kubectl config current-context
Show active cluster context.
kubectl get pods
List pods.
kubectl get all
Common workload/service objects.
kubectl describe pod NAME
Detailed pod diagnostics.
kubectl logs -f POD
Follow pod logs.
kubectl exec -it POD -- sh
Shell inside pod.
kubectl apply -f file.yaml
Create/update resources.
kubectl delete -f file.yaml
Delete resources from manifest.
kubectl rollout status deploy/APP
Watch deployment rollout.
kubectl port-forward svc/app 8080:80
Forward local port to service.
Cloud CLI Identity Checks
aws configure
Configure AWS CLI credentials/defaults.
aws sts get-caller-identity
Confirm current AWS identity.
aws s3 ls
List accessible S3 buckets.
az login
Sign in to Azure CLI.
az account show
Current Azure subscription/account.
az group list -o table
List resource groups.
gcloud auth login
Sign in to Google Cloud CLI.
gcloud config get-value project
Show active GCP project.
gcloud projects list
List accessible projects.
NOTE
Cloud commands require the vendor CLI plus appropriate account permissions. Prefer SSO/short-lived credentials where your organization supports them.
Ports Developers See Often
Fast Troubleshooting Loop
Fast troubleshooting sequence
Run these checks in order to confirm location, source state, runtime availability, dependencies, ports, containers, logs, and HTTP response.
Example
pwd && ls -la
git status
node -v
python --version
npm -v
docker --version
npm ci
printenv | sort
lsof -i :PORT
docker compose ps
docker compose logs -f
curl -I localhost:PORTHigh-Risk Commands: Slow Down
rm -rf PATH
Permanently removes files.
git reset --hard
Discards uncommitted changes.
git clean -fd
Deletes untracked files/directories.
docker compose down -v
Can erase local database volumes.
DROP DATABASE / DROP TABLE
Deletes database structures/data.
DELETE / UPDATE without WHERE
Can affect every row.
sudo
Runs with elevated privileges.
NOTE
Before destructive commands: verify
pwd, inspect the exact path/resource, make a backup when data matters, and prefer reversible commands when possible.