# dotenv — Load Environment Variables from .env Files

> dotenv is a zero-dependency Node.js module that loads environment variables from a .env file into process.env, separating config from code.

## Install

Save as a script file and run:

# dotenv — Load Environment Variables from .env Files

## Quick Use
```bash
npm install dotenv
```
```javascript
require('dotenv').config();
console.log(process.env.DATABASE_URL);
```
```
# .env
DATABASE_URL=postgres://localhost:5432/mydb
API_KEY=sk-abc123
```

## Introduction
dotenv is a small zero-dependency module that reads key-value pairs from a `.env` file and injects them into `process.env`. It is the standard approach for managing environment-specific configuration in Node.js without hardcoding secrets in source code.

## What dotenv Does
- Parses `.env` files following a `KEY=VALUE` format
- Populates `process.env` with the parsed variables
- Does not override existing environment variables by default
- Supports multiline values, quoted strings, and inline comments
- Works with `dotenv-expand` for variable interpolation within `.env` files

## Architecture Overview
dotenv reads the specified file (default `.env` in the project root), parses each line using a regex-based parser that handles quoting and escaping, and assigns the result to `process.env`. It runs synchronously at startup so variables are available before any other module reads them. The parser handles single-quoted, double-quoted, and backtick-quoted values, each with different escape semantics.

## Self-Hosting & Configuration
- Install via `npm install dotenv` and call `require('dotenv').config()` at the top of your entry file
- Use `--require dotenv/config` as a Node.js CLI flag to preload without changing code
- Pass `{ path: '.env.local' }` to load from a custom file path
- Set `{ override: true }` to let `.env` values overwrite existing environment variables
- Add `.env` to `.gitignore` and commit a `.env.example` template instead

## Key Features
- Zero dependencies for a minimal footprint
- Does not overwrite pre-existing environment variables (safe for production)
- Supports multiline values enclosed in double or single quotes
- Companion `dotenv-expand` package adds variable expansion (`${VAR}` syntax)
- Preload mode via `node --require dotenv/config app.js` for zero-code integration

## Comparison with Similar Tools
- **dotenvx** — encrypted `.env` files with multi-environment support; dotenv is simpler and unencrypted
- **direnv** — shell-level env loading triggered on `cd`; dotenv loads inside the Node.js process
- **cross-env** — sets env vars inline in npm scripts; dotenv reads from files for larger config sets
- **env-cmd** — executes commands with env from a file; dotenv integrates directly into Node.js code
- **Vault / SOPS** — secret managers for production; dotenv is meant for development and simple deployments

## FAQ
**Q: Should I commit my .env file to Git?**
A: No. Add `.env` to `.gitignore`. Commit a `.env.example` with placeholder values so other developers know which variables to set.

**Q: Does dotenv work with TypeScript?**
A: Yes. Install `dotenv` and call `config()` at the top of your entry file. Type declarations are included.

**Q: How do I use different .env files per environment?**
A: Call `dotenv.config({ path: '.env.production' })` or use a wrapper like `dotenv-flow` that loads `.env`, `.env.local`, `.env.{NODE_ENV}` in order.

**Q: Does dotenv work in the browser?**
A: Not directly. Bundlers like Vite and webpack have their own env variable handling. dotenv is for Node.js server-side code.

## Sources
- https://github.com/motdotla/dotenv
- https://github.com/motdotla/dotenv#readme

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Source: https://tokrepo.com/en/workflows/41b052cf-40e4-11f1-9bc6-00163e2b0d79
Author: Script Depot