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Python and Node.js CLI

Installing and running Python and Node.js from the command line, managing packages with pip/npm, using virtual environments, and version management.

Python

Installation

# Linux (Debian/Ubuntu)
sudo apt update
sudo apt install python3 python3-pip python3-venv

# Verify
python3 --version
pip3 --version

Windows: download from python.org, check "Add Python to PATH". Or install from Microsoft Store.

Running Python

python3                         # interactive REPL
python3 script.py               # run script
python3 -c "print('hello')"    # inline command
python3 -m http.server          # run module

# Windows
py script.py                    # Windows launcher
py -3.11 script.py              # specific version

pip - Package Manager

pip install requests            # install
pip install requests==2.31.0    # specific version
pip install -r requirements.txt # from requirements file
pip uninstall requests
pip list                        # installed packages
pip show requests               # package info
pip freeze > requirements.txt   # save current packages
pip install --upgrade pip       # upgrade pip itself

Virtual Environments

python3 -m venv .venv           # create
source .venv/bin/activate       # activate (Linux/macOS)
.venv\Scripts\activate          # activate (Windows cmd)

# After activation: prompt shows (.venv)
pip install package             # installs only in venv
deactivate                      # exit venv

uv - Fast Alternative

curl -LsSf https://astral.sh/uv/install.sh | sh
uv venv                         # create venv
uv pip install requests         # 10-100x faster than pip
uv run script.py                # run without activating

Shebang for Scripts

#!/usr/bin/env python3

chmod +x script.py && ./script.py

Environment Variables

MY_VAR=hello python3 script.py  # pass for single run
export MY_VAR=hello             # export to session

import os
value = os.environ.get("MY_VAR", "default")

Node.js

Installation

# Via NodeSource (recommended)
curl -fsSL https://deb.nodesource.com/setup_20.x | sudo -E bash -
sudo apt install nodejs

# Via nvm (version manager)
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.0/install.sh | bash
source ~/.bashrc
nvm install --lts
nvm use 20
nvm alias default 20

Windows: download from nodejs.org or use nvm-windows.

Running Node.js

node                    # REPL
node script.js          # run script
node -e "console.log('hi')"  # inline

npm - Package Manager

npm init -y                     # create package.json
npm install express             # add dependency
npm install -D jest             # devDependency
npm install                     # install all from package.json
npm install -g nodemon          # install globally
npm uninstall express
npm list                        # local packages
npm list -g                     # global packages
npm outdated                    # show outdated
npm update                      # update packages
npm run dev                     # run script from package.json
npx create-react-app my-app    # run without installing

package.json Scripts

{
  "scripts": {
    "start": "node server.js",
    "dev": "nodemon server.js",
    "test": "jest",
    "build": "tsc"
  }
}

Comparison

Task Python Node.js
Run script python3 script.py node script.js
REPL python3 node
Package manager pip npm / yarn / pnpm
Package file requirements.txt / pyproject.toml package.json
Version manager pyenv / uv nvm
Virtual env python3 -m venv node_modules per project
Run without install python3 -m module npx package

Gotchas

  • pip install without venv installs system-wide - always use virtual environments
  • nvm is shell-specific; restart terminal after install
  • npm install -g may need sudo on Linux (or fix npm prefix)
  • Python python vs python3: on some systems python is Python 2
  • npx downloads and runs packages - security risk if package name is typo-squatted
  • Node.js version matters significantly - use LTS for production

See Also

  • [[package-management]] - System package managers (apt, yum)
  • [[bash-scripting]] - Shell scripting
  • [[terminal-basics]] - Shell fundamentals