What is the regex for environment variable name?

The regex pattern for environment variable name is `^[A-Z_][A-Z0-9_]*$`. This pattern validates standard environment variable name (uppercase with underscores).

How do I use this regex in JavaScript?

In JavaScript, create the regex with `const regex = /^[A-Z_][A-Z0-9_]*$/;` and test with `regex.test(yourValue)`. It returns `true` if the value matches.

How do I use this regex in Python?

In Python, use `import re; re.match(r'^[A-Z_][A-Z0-9_]*$', value)`. The raw string prefix (`r`) prevents Python from interpreting backslashes as escape characters.

Is this regex case-sensitive?

By default, yes. To make it case-insensitive, add the `i` flag in JavaScript (`/^[A-Z_][A-Z0-9_]*$/i`) or use `re.IGNORECASE` in Python.

Regex for Environment Variable Name

Regex Pattern

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

Standard environment variable name (uppercase with underscores)

Quick Answer

The regex pattern for environment variable name is `^[A-Z_][A-Z0-9_]*$`. Standard environment variable name (uppercase with underscores). This works in JavaScript, Python, Ruby, PHP, Java, and most regex engines that support PCRE syntax.

Test Examples

Input	Result
PATH	✓ Matches
HOME	✓ Matches
DATABASE_URL	✓ Matches
NODE_ENV	✓ Matches
_PRIVATE	✓ Matches
path	✗ No match
my-var	✗ No match
123VAR	✗ No match
has space	✗ No match

Code Examples

javascript

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

python

import re
pattern = r'^[A-Z_][A-Z0-9_]*$'
if re.match(pattern, value):
    print("valid")

ruby

pattern = /^[A-Z_][A-Z0-9_]*$/
if value =~ pattern
  puts "valid"
end

php

if (preg_match('/^[A-Z_][A-Z0-9_]*$/', $value)) {
    echo "valid";
}

java

String pattern = "^[A-Z_][A-Z0-9_]*$";
boolean isValid = value.matches(pattern);

Frequently Asked Questions

Related Regex Patterns

JavaScript Variable Name

Valid JavaScript variable/identifier name

Python Variable Name

Valid Python identifier name

CSS Class Name

Valid CSS class name (starts with letter, underscore, or hyphen)

CSS ID Selector

CSS ID selector starting with #

JSON Key

JSON object key (quoted string followed by colon)

Semantic Version (Strict)

Strict semantic versioning (MAJOR.MINOR.PATCH)