Process ID (PID) Regex for Python

What this pattern does

This page provides a well-structured, multi-part regular expression for matching process id (pid), 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

# Process ID (PID)
# ReDoS-safe | RegexVault — Dev & Systems > Shell

import re

process_id_pid_pattern = re.compile(r'^(?:[1-9][0-9]{0,5}|[1-3][0-9]{6}|4194304)$')

def validate_process_id_pid(value: str) -> bool:
    return bool(process_id_pid_pattern.fullmatch(value))

# Example
print(validate_process_id_pid("1"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Dev & Systems > Shell 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

PID 1 is always init/systemd. Linux defaults to max PID 32768 (/proc/sys/kernel/pid_max), configurable up to 4194304 (2^22). PID 0 is not a valid kill/signal target.