Find Zombie Processes on Linux with Python

Parse the output of `ps -eo pid,stat,comm` to detect processes in zombie state (Z) on a Linux system and report their PIDs and commands.

Medium Python 3.9+ Jun 28, 2026 Automation & scripting 2 views 0 copies

linux process monitoring subprocess system administration

Python code

31 lines

Python 3.9+

#!/usr/bin/env python3
import os
import subprocess

def find_zombie_processes():
    """Find zombie processes (state 'Z') running on Linux."""
    try:
        result = subprocess.run(['ps', '-eo', 'pid,stat,comm'], capture_output=True, text=True, check=True)
        zombies = []
        for line in result.stdout.strip().split('\n')[1:]:  # Skip header
            if line.strip():
                parts = line.split()
                if len(parts) >= 3:
                    pid, state, command = parts[0], parts[1], ' '.join(parts[2:])
                    if 'Z' in state:
                        zombies.append((int(pid), command))
        return zombies
    except subprocess.CalledProcessError:
        return []

def main():
    zombies = find_zombie_processes()
    if zombies:
        print("Zombie processes found:")
        for pid, command in zombies:
            print(f"  PID {pid}: {command}")
    else:
        print("No zombie processes found.")

if __name__ == "__main__":
    main()

Output

stdout

Zombie processes found:
  PID 1234: defunct_program
  PID 5678: old_service

How it works

Zombie processes are terminated but still have an entry in the process table because their parent has not read their exit status. The ps -eo pid,stat,comm command lists each process with its PID, state code, and command name. State Z indicates a zombie. By iterating over the output lines and checking for 'Z' in the state field, we collect all zombies. Using subprocess.run with check=True ensures errors (e.g., if ps is unavailable) are caught gracefully.

Common mistakes

Parsing header line as a process entry (always skip the first line).
Assuming the state field always appears as a single character (it can be multi-character like 'Zs' for zombie+session leader).
Forgetting to handle the case where `ps` output columns might not have spaces consistently.

Variations

Read the /proc filesystem directly by listing directories under /proc and checking the `status` or `stat` file for state.
Use the `pgrep` or `psutil` third-party library for cross-platform process monitoring.

Real-world use cases

Integrate into a system health monitoring script that alerts when zombie processes accumulate on a production server.
Use inside a CI/CD pipeline to check for orphaned processes after test runs and clean them up automatically.
Wrap in a cron job that logs zombie process counts each hour for capacity planning and anomaly detection.

Find Zombie Processes on Linux with Python

Python code

Output

How it works

Common mistakes

Variations

Real-world use cases

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Python code

Output

How it works

Common mistakes

Variations

Real-world use cases

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