POSIX Environment Variable Name (Uppercase Convention) Regex for Python

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching posix environment variable name (uppercase convention), ported and verified for Python. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# POSIX Environment Variable Name (Uppercase Convention)
# ReDoS-safe | RegexVault — Dev & Systems > Environment

import re

posix_environment_variable_name_uppercase_convention_pattern = re.compile(r'^[A-Z_][A-Z0-9_]{0,254}$')

def validate_posix_environment_variable_name_uppercase_convention(value: str) -> bool:
    return bool(posix_environment_variable_name_uppercase_convention_pattern.fullmatch(value))

# Example
print(validate_posix_environment_variable_name_uppercase_convention("PATH"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Dev & Systems > Environment category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

POSIX variables are case-sensitive and conventionally uppercase. Lowercase variables (PATH vs path) are different on Linux. On Windows, environment variables are case-insensitive.