Regex for Environment Variable Name

Validates UPPER_SNAKE_CASE environment variable names starting with a letter.

Pattern

/^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$/

Live Tester

Enter a string to test

Examples

✓ DATABASE_URL

✓ NODE_ENV

✓ AWS_ACCESS_KEY_ID

✗ database_url

✗ 123_VAR

✗ _LEADING_UNDERSCORE

Pattern Breakdown

^[A-Z] — starts with an uppercase letter

[A-Z0-9]* — followed by uppercase letters or digits

(_[A-Z0-9]+)*$ — optional underscore-separated segments

Code Snippets

Javascript

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

Python

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

Php

$pattern = '/^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$/';
preg_match($pattern, "DATABASE_URL"); // 1

Related Patterns

Email Address /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/ URL /^https?:\/\/(www\.)?[a-zA-Z0-9@:%._+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([a-zA-Z0-9()@:%_+.~#?&/=-]*)$/ Phone Number (International) /^\+?[1-9]\d{1,14}$/ Phone Number (US) /^$?[2-9]\d{2}$?[-.\s]?\d{3}[-.\s]?\d{4}$/ Phone Number (EU) /^\+?[1-9][0-9]{0,3}[\s.-]?$?[0-9]{1,5}$?[\s.-]?[0-9]{1,5}[\s.-]?[0-9]{1,5}$/ IPv4 Address /^((25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(25[0-5]|2[0-4]\d|[01]?\d\d?)$/

Frequently Asked Questions

What is the regex for Environment Variable Name?▾

The regex pattern for Environment Variable Name is /^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$/. Validates UPPER_SNAKE_CASE environment variable names starting with a letter.

How do I use the Environment Variable Name regex in JavaScript?▾

In JavaScript you create the pattern with a regex literal or the RegExp constructor and call .test() to check a string against it. A ready-to-copy example is shown in the Code Snippets section above, alongside Python and PHP versions.

What does the Environment Variable Name pattern match?▾

It matches strings like DATABASE_URL; it rejects strings like database_url. See the Examples section above for the full list of matching and non-matching cases.