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Environment VariableRegex — Pattern, Examples & Code

^[A-Z_][A-Z0-9_]*$

What it matches / doesn't match

Matches ✅Does not match ❌
●DATABASE_URL●lowercase_key
●NEXT_PUBLIC_API_KEY●1STARTS_WITH_DIGIT
●_INTERNAL●HAS-HYPHEN

How it works

Matches POSIX-compliant environment variable names: start with an uppercase letter or underscore, followed by any combination of uppercase letters, digits, and underscores. Lowercase letters are rejected since env var names are conventionally uppercase. This covers common conventions like DATABASE_URL, NEXT_PUBLIC_API_KEY, and __INTERNAL_VAR.

Code Usage

JavaScript

const regex = /^[A-Z_][A-Z0-9_]*$/;
regex.test("DATABASE_URL"); // true

Python

import re
pattern = re.compile(r'^[A-Z_][A-Z0-9_]*$')
bool(pattern.match("DATABASE_URL"))  # True

Go

import "regexp"
r := regexp.MustCompile(`^[A-Z_][A-Z0-9_]*$`)
r.MatchString("DATABASE_URL") // true

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FAQ

What does the Environment Variable regex pattern match?

Matches POSIX-compliant environment variable names: start with an uppercase letter or underscore, followed by any combination of uppercase letters, digits, and underscores. Lowercase letters are rejected since env var names are conventionally uppercase. This covers common conventions like DATABASE_URL, NEXT_PUBLIC_API_KEY, and __INTERNAL_VAR.

How do I use the Environment Variable regex in JavaScript?

const regex = /^[A-Z_][A-Z0-9_]*$/; regex.test("DATABASE_URL"); // true

Can I use the Environment Variable regex in Python?

Yes. import re pattern = re.compile(r'^[A-Z_][A-Z0-9_]*$') bool(pattern.match("DATABASE_URL")) # True