Env Vars Cheatsheet - .env Config & dotenv Usage
The format and pitfalls you forget when writing .env or loading config with dotenv, grouped by definition, framework integration and security, with copy-ready examples.
Back to Config FormatsDefinition 6
KEY=value定义variable（号两侧不要有空格）
KEY="value with space"含空格or特殊字符需加引号
KEY='literal $NOT_EXPANDED'单引号内不做variable展开
KEY=${OTHER}_suffix双引号内可引用其他variable
# comment井号beginning为注释行
export KEY=valueSet&Export为env var
Reading 5
echo $KEYShell 中Readvariable（Linux/macOS）
echo %KEY%Windows cmd Readvariable
$env:KEYPowerShell Readvariable
process.env.KEYNode.js Read
os.getenv("KEY")Python Read
dotenv Usage 4
require('dotenv').config()Node 加载 .env 到 process.env
import 'dotenv/config'ESM 写法加载 .env
dotenv.config({ path: '.env.local' })指定自定义File路径
python-dotenv load_dotenv()Python 加载 .env
Multi-env Files 5
.env默认环境（勿提交到 git）
.env.local本地overwrite（优先级更高）
.env.development开发环境
.env.production生产环境
.env.exampleexampletemplate，可提交，不含真实密钥
Security FAQ 4
不要提交密钥把 .env 加入 .gitignore，用 .env.example 提供template
区分大小写KEY & key 是不同variable
类型转换所有值都是string，数字需自行 parseInt/Number()
换行需转义多行值用引号package裹or使用
💡 Tips
- No spaces around the equals sign (KEY=value, not KEY = value).
- Add .env to .gitignore; commit secrets only via .env.example.
- All values are strings — convert numbers with Number()/parseInt().
- For multi-line values, wrap in quotes or use \n for a newline.
Official References
Commands are compiled from the official docs below. Click to verify the latest usage.
Maintained by LaoHand
Publicly updated on Aug 2, 2026, continuously proofread against official docs.
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